diff --git a/api_guard/dist/types/index.d.ts b/api_guard/dist/types/index.d.ts
index 833f365b89..18585e7b12 100644
--- a/api_guard/dist/types/index.d.ts
+++ b/api_guard/dist/types/index.d.ts
@@ -301,7 +301,7 @@ export declare class Observable<T> implements Subscribable<T> {
     pipe<A, B, C, D, E, F, G, H>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>, op3: OperatorFunction<B, C>, op4: OperatorFunction<C, D>, op5: OperatorFunction<D, E>, op6: OperatorFunction<E, F>, op7: OperatorFunction<F, G>, op8: OperatorFunction<G, H>): Observable<H>;
     pipe<A, B, C, D, E, F, G, H, I>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>, op3: OperatorFunction<B, C>, op4: OperatorFunction<C, D>, op5: OperatorFunction<D, E>, op6: OperatorFunction<E, F>, op7: OperatorFunction<F, G>, op8: OperatorFunction<G, H>, op9: OperatorFunction<H, I>): Observable<I>;
     pipe<A, B, C, D, E, F, G, H, I>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>, op3: OperatorFunction<B, C>, op4: OperatorFunction<C, D>, op5: OperatorFunction<D, E>, op6: OperatorFunction<E, F>, op7: OperatorFunction<F, G>, op8: OperatorFunction<G, H>, op9: OperatorFunction<H, I>, ...operations: OperatorFunction<any, any>[]): Observable<unknown>;
-    subscribe(observer?: PartialObserver<T>): Subscription;
+    subscribe(observer?: Partial<Observer<T>>): Subscription;
     subscribe(next: null | undefined, error: null | undefined, complete: () => void): Subscription;
     subscribe(next: null | undefined, error: (error: any) => void, complete?: () => void): Subscription;
     subscribe(next: (value: T) => void, error: null | undefined, complete: () => void): Subscription;
@@ -443,10 +443,11 @@ export declare class Subject<T> extends Observable<T> implements SubscriptionLik
     static create: (...args: any[]) => any;
 }
 
-export declare type SubjectLike<T> = Observer<T> & Subscribable<T>;
+export interface SubjectLike<T> extends Observer<T>, Subscribable<T> {
+}
 
 export interface Subscribable<T> {
-    subscribe(observer: Observer<T>): Unsubscribable;
+    subscribe(observer: Partial<Observer<T>>): Unsubscribable;
 }
 
 export declare type SubscribableOrPromise<T> = Subscribable<T> | Subscribable<never> | PromiseLike<T> | InteropObservable<T>;
diff --git a/api_guard/dist/types/operators/index.d.ts b/api_guard/dist/types/operators/index.d.ts
index 24e43da16b..3a85ca4d31 100644
--- a/api_guard/dist/types/operators/index.d.ts
+++ b/api_guard/dist/types/operators/index.d.ts
@@ -60,10 +60,7 @@ export declare function concatMapTo<T, R, O extends ObservableInput<any>>(observ
 
 export declare function concatWith<T, A extends readonly unknown[]>(...otherSources: [...ObservableInputTuple<A>]): OperatorFunction<T, T | A[number]>;
 
-export declare function connect<T, R>({ connector, setup, }: {
-    connector?: () => SubjectLike<T>;
-    setup: (shared: Observable<T>) => ObservableInput<R>;
-}): OperatorFunction<T, R>;
+export declare function connect<T, R>(selector: (shared: Observable<T>) => ObservableInput<R>, config?: ConnectConfig<T>): OperatorFunction<T, R>;
 
 export declare function count<T>(predicate?: (value: T, index: number) => boolean): OperatorFunction<T, number>;
 
@@ -253,7 +250,7 @@ export declare function scan<V, A, S>(accumulator: (acc: A | S, value: V, index:
 export declare function sequenceEqual<T>(compareTo: Observable<T>, comparator?: (a: T, b: T) => boolean): OperatorFunction<T, boolean>;
 
 export declare function share<T>(): MonoTypeOperatorFunction<T>;
-export declare function share<T, R = T>(options: ShareOptions<T, R>): OperatorFunction<T, R>;
+export declare function share<T>(options: ShareConfig<T>): MonoTypeOperatorFunction<T>;
 
 export declare function shareReplay<T>(config: ShareReplayConfig): MonoTypeOperatorFunction<T>;
 export declare function shareReplay<T>(bufferSize?: number, windowTime?: number, scheduler?: SchedulerLike): MonoTypeOperatorFunction<T>;
diff --git a/spec/deprecation-equivalents/multicasting-deprecations-spec.ts b/spec/deprecation-equivalents/multicasting-deprecations-spec.ts
index 26feef216c..d9024c44fc 100644
--- a/spec/deprecation-equivalents/multicasting-deprecations-spec.ts
+++ b/spec/deprecation-equivalents/multicasting-deprecations-spec.ts
@@ -63,12 +63,7 @@ describe('multicasting equivalent tests', () => {
   testEquivalents(
     'publish(fn) and connect({ setup: fn })',
     (source) => source.pipe(publish(fn)),
-    (source) =>
-      source.pipe(
-        connect({
-          setup: fn,
-        })
-      )
+    (source) => source.pipe(connect(fn))
   );
 
   testEquivalents(
@@ -76,7 +71,7 @@ describe('multicasting equivalent tests', () => {
     (source) => source.pipe(publishReplay(3, 10, fn)),
     (source) => {
       const subject = new ReplaySubject(3, 10);
-      return source.pipe(connect({ connector: () => subject, setup: fn }));
+      return source.pipe(connect(fn, { connector: () => subject }));
     }
   );
 
diff --git a/spec/operators/connect-spec.ts b/spec/operators/connect-spec.ts
index a4cf50f5f8..23761d54e9 100644
--- a/spec/operators/connect-spec.ts
+++ b/spec/operators/connect-spec.ts
@@ -11,37 +11,33 @@ describe('connect', () => {
     rxTest = new TestScheduler(observableMatcher);
   });
 
-  it('should connect a source through a setup function', () => {
+  it('should connect a source through a selector function', () => {
     rxTest.run(({ cold, time, expectObservable }) => {
       const source = cold('---a----b-----c---|');
       const d = time('        ---|');
       const expected = '   ---a--a-b--b--c--c|';
 
-      const result = source.pipe(
-        connect({
-          setup: (shared) => {
-            return merge(shared.pipe(delay(d)), shared);
-          },
-        })
-      );
+      const result = source.pipe(connect((shared) => merge(shared.pipe(delay(d)), shared)));
 
       expectObservable(result).toBe(expected);
     });
   });
 
-  it('should connect a source through a setup function and use the provided connector', () => {
+  it('should connect a source through a selector function and use the provided connector', () => {
     rxTest.run(({ cold, time, expectObservable }) => {
       const source = cold('--------a---------b---------c-----|');
       const d = time('             ---|');
       const expected = '   S--S----a--a------b--b------c--c--|';
 
       const result = source.pipe(
-        connect({
-          connector: () => new BehaviorSubject('S'),
-          setup: (shared) => {
+        connect(
+          (shared) => {
             return merge(shared.pipe(delay(d)), shared);
           },
-        })
+          {
+            connector: () => new BehaviorSubject('S'),
+          }
+        )
       );
 
       expectObservable(result).toBe(expected);
diff --git a/spec/schedulers/TestScheduler-spec.ts b/spec/schedulers/TestScheduler-spec.ts
index 7d91068bbc..ce3b515cef 100644
--- a/spec/schedulers/TestScheduler-spec.ts
+++ b/spec/schedulers/TestScheduler-spec.ts
@@ -397,13 +397,16 @@ describe('TestScheduler', () => {
         expect(expectObservable).to.be.a('function');
         expect(expectSubscriptions).to.be.a('function');
 
-        const obs1 = cold('-a-c-e|');
+      const obs1 = cold('-a-c-e|');
         const obs2 = hot(' ^-b-d-f|');
         const output = merge(obs1, obs2);
         const expected = ' -abcdef|';
 
         expectObservable(output).toBe(expected);
         expectObservable(output).toEqual(cold(expected));
+        // There are two subscriptions to each of these, because we merged
+        // them together, then we subscribed to the merged result once
+        // to check `toBe` and another time to check `toEqual`.
         expectSubscriptions(obs1.subscriptions).toBe(['^-----!', '^-----!']);
         expectSubscriptions(obs2.subscriptions).toBe(['^------!', '^------!']);
       });
diff --git a/src/internal/Observable.ts b/src/internal/Observable.ts
index ea64715de8..c78bd9e90c 100644
--- a/src/internal/Observable.ts
+++ b/src/internal/Observable.ts
@@ -4,7 +4,7 @@
 import { Operator } from './Operator';
 import { SafeSubscriber, Subscriber } from './Subscriber';
 import { isSubscription, Subscription } from './Subscription';
-import { TeardownLogic, OperatorFunction, PartialObserver, Subscribable, Observer } from './types';
+import { TeardownLogic, OperatorFunction, Subscribable, Observer } from './types';
 import { observable as Symbol_observable } from './symbol/observable';
 import { pipeFromArray } from './util/pipe';
 import { config } from './config';
@@ -68,7 +68,7 @@ export class Observable<T> implements Subscribable<T> {
     return observable;
   }
 
-  subscribe(observer?: PartialObserver<T>): Subscription;
+  subscribe(observer?: Partial<Observer<T>>): Subscription;
   /** @deprecated Use an observer instead of a complete callback */
   subscribe(next: null | undefined, error: null | undefined, complete: () => void): Subscription;
   /** @deprecated Use an observer instead of an error callback */
@@ -202,7 +202,7 @@ export class Observable<T> implements Subscribable<T> {
    * @method subscribe
    */
   subscribe(
-    observerOrNext?: PartialObserver<T> | ((value: T) => void) | null,
+    observerOrNext?: Partial<Observer<T>> | ((value: T) => void) | null,
     error?: ((error: any) => void) | null,
     complete?: (() => void) | null
   ): Subscription {
diff --git a/src/internal/Subscriber.ts b/src/internal/Subscriber.ts
index ab16054b3e..f5a4555c40 100644
--- a/src/internal/Subscriber.ts
+++ b/src/internal/Subscriber.ts
@@ -1,6 +1,6 @@
 /** @prettier */
 import { isFunction } from './util/isFunction';
-import { Observer, PartialObserver, ObservableNotification } from './types';
+import { Observer, ObservableNotification } from './types';
 import { isSubscription, Subscription } from './Subscription';
 import { config } from './config';
 import { reportUnhandledError } from './util/reportUnhandledError';
@@ -126,7 +126,7 @@ export class Subscriber<T> extends Subscription implements Observer<T> {
 
 export class SafeSubscriber<T> extends Subscriber<T> {
   constructor(
-    observerOrNext?: PartialObserver<T> | ((value: T) => void) | null,
+    observerOrNext?: Partial<Observer<T>> | ((value: T) => void) | null,
     error?: ((e?: any) => void) | null,
     complete?: (() => void) | null
   ) {
diff --git a/src/internal/observable/connectable.ts b/src/internal/observable/connectable.ts
index d2ccdf9c11..df7aa81a7c 100644
--- a/src/internal/observable/connectable.ts
+++ b/src/internal/observable/connectable.ts
@@ -6,7 +6,11 @@ import { Subscription } from '../Subscription';
 import { Observable } from '../Observable';
 import { defer } from './defer';
 
-export type ConnectableObservableLike<T> = Observable<T> & {
+/**
+ * An observable with a `connect` method that is used to create a subscription
+ * to an underlying source, connecting it with all consumers via a multicast.
+ */
+export interface ConnectableObservableLike<T> extends Observable<T> {
   /**
    * (Idempotent) Calling this method will connect the underlying source observable to all subscribed consumers
    * through an underlying {@link Subject}.
@@ -14,7 +18,7 @@ export type ConnectableObservableLike<T> = Observable<T> & {
    * severing notifications to all consumers.
    */
   connect(): Subscription;
-};
+}
 
 /**
  * Creates an observable that multicasts once `connect()` is called on it.
diff --git a/src/internal/operators/connect.ts b/src/internal/operators/connect.ts
index 1379214dcd..7e7357fbdc 100644
--- a/src/internal/operators/connect.ts
+++ b/src/internal/operators/connect.ts
@@ -6,13 +6,20 @@ import { from } from '../observable/from';
 import { operate } from '../util/lift';
 import { fromSubscribable } from '../observable/fromSubscribable';
 
+export interface ConnectConfig<T> {
+  /**
+   * A factory function used to create the Subject through which the source
+   * is multicast. By default this creates a {@link Subject}.
+   */
+  connector: () => SubjectLike<T>;
+}
+
 /**
- * The default connector function used for `connect`.
- * A factory function that will create a {@link Subject}.
+ * The default configuration for `connect`.
  */
-function defaultConnector<T>() {
-  return new Subject<T>();
-}
+const DEFAULT_CONFIG: ConnectConfig<unknown> = {
+  connector: () => new Subject<unknown>(),
+};
 
 /**
  * Creates an observable by multicasting the source within a function that
@@ -25,16 +32,16 @@ function defaultConnector<T>() {
  * has returned, if the source is synchronous its internal reference count will jump from
  * 0 to 1 back to 0 and reset.
  *
- * To use `connect`, you provide a `setup` function via configuration that will give you
+ * To use `connect`, you provide a `selector` function that will give you
  * a multicast observable that is not yet connected. You then use that multicast observable
  * to create a resulting observable that, when subscribed, will set up your multicast. This is
  * generally, but not always, accomplished with {@link merge}.
  *
- * Note that using a {@link takeUntil} inside of `connect`'s `setup` _might_ mean you were looking
+ * Note that using a {@link takeUntil} inside of `connect`'s `selector` _might_ mean you were looking
  * to use the {@link takeWhile} operator instead.
  *
- * When you subscribe to the result of `connect`, the `setup` function will be called. After
- * the `setup` function returns, the observable it returns will be subscribed to, _then_ the
+ * When you subscribe to the result of `connect`, the `selector` function will be called. After
+ * the `selector` function returns, the observable it returns will be subscribed to, _then_ the
  * multicast will be connected to the source.
  *
  * ### Example
@@ -53,14 +60,12 @@ function defaultConnector<T>() {
  * });
  *
  * source$.pipe(
- *  connect({
- *    // Notice in here we're merging three subscriptions to `shared$`.
- *    setup: (shared$) => merge(
+ *  // Notice in here we're merging 3 subscriptions to `shared$`.
+ *  connect((shared$) => merge(
  *      shared$.pipe(map(n => `all ${n}`)),
  *      shared$.pipe(filter(n => n % 2 === 0), map(n => `even ${n}`)),
  *      shared$.pipe(filter(n => n % 2 === 1), map(n => `odd ${n}`)),
- *    )
- *  })
+ *  ))
  * )
  * .subscribe(console.log);
  *
@@ -83,29 +88,21 @@ function defaultConnector<T>() {
  * "odd 5"
  * ```
  *
+ * @param selector A function used to set up the multicast. Gives you a multicast observable
+ * that is not yet connected. With that, you're expected to create and return
+ * and Observable, that when subscribed to, will utilize the multicast observable.
+ * After this function is executed -- and its return value subscribed to -- the
+ * the operator will subscribe to the source, and the connection will be made.
  * @param param0 The configuration object for `connect`.
  */
-export function connect<T, R>({
-  connector = defaultConnector,
-  setup,
-}: {
-  /**
-   * A factory function used to create the Subject through which the source
-   * is multicast. By default this creates a {@link Subject}.
-   */
-  connector?: () => SubjectLike<T>;
-  /**
-   * A function used to set up the multicast. Gives you a multicast observable
-   * that is not yet connected. With that, you're expected to create and return
-   * and Observable, that when subscribed to, will utilize the multicast observable.
-   * After this function is executed -- and its return value subscribed to -- the
-   * the operator will subscribe to the source, and the connection will be made.
-   */
-  setup: (shared: Observable<T>) => ObservableInput<R>;
-}): OperatorFunction<T, R> {
+export function connect<T, R>(
+  selector: (shared: Observable<T>) => ObservableInput<R>,
+  config: ConnectConfig<T> = DEFAULT_CONFIG
+): OperatorFunction<T, R> {
+  const { connector } = config;
   return operate((source, subscriber) => {
     const subject = connector();
-    from(setup(fromSubscribable(subject))).subscribe(subscriber);
+    from(selector(fromSubscribable(subject))).subscribe(subscriber);
     subscriber.add(source.subscribe(subject));
   });
 }
diff --git a/src/internal/operators/multicast.ts b/src/internal/operators/multicast.ts
index 2c8e3e7234..1f5ec936d0 100644
--- a/src/internal/operators/multicast.ts
+++ b/src/internal/operators/multicast.ts
@@ -58,9 +58,9 @@ export function multicast<T>(subjectFactory: () => Subject<T>): UnaryFunction<Ob
  * {@link connect} operator.
  *
  * @param subjectFactory A factory that creates the subject used to multicast.
- * @param selector A setup function to setup the multicast
+ * @param selector A function to setup the multicast and select the output.
  * @deprecated To be removed in version 8. Please use the new {@link connect} operator.
- * `multicast(fn1, fn2)` is equivalent to `connect({ connector: fn1, setup: fn2 })`.
+ * `multicast(subjectFactor, selector)` is equivalent to `connect(selector, { connector: subjectFactory })`.
  */
 export function multicast<T, O extends ObservableInput<any>>(
   subjectFactory: () => Subject<T>,
@@ -77,9 +77,8 @@ export function multicast<T, R>(
     // If a selector function is provided, then we're a "normal" operator that isn't
     // going to return a ConnectableObservable. We can use `connect` to do what we
     // need to do.
-    return connect({
+    return connect(selector, {
       connector: subjectFactory,
-      setup: selector,
     });
   }
 
diff --git a/src/internal/operators/publish.ts b/src/internal/operators/publish.ts
index 2d8414044b..2dfa9ebfb2 100644
--- a/src/internal/operators/publish.ts
+++ b/src/internal/operators/publish.ts
@@ -28,7 +28,7 @@ export function publish<T>(): UnaryFunction<Observable<T>, ConnectableObservable
  * @param selector A function used to setup multicasting prior to automatic connection.
  *
  * @deprecated To be removed in version 8. Use the new {@link connect} operator.
- * If you're using `publish(fn)`, it is equivalent to `connect({ setup: fn })`.
+ * If you're using `publish(fn)`, it is equivalent to `connect(fn)`.
  */
 export function publish<T, O extends ObservableInput<any>>(selector: (shared: Observable<T>) => O): OperatorFunction<T, ObservedValueOf<O>>;
 
@@ -79,10 +79,5 @@ export function publish<T, O extends ObservableInput<any>>(selector: (shared: Ob
  * @return A ConnectableObservable that upon connection causes the source Observable to emit items to its Observers.
  */
 export function publish<T, R>(selector?: OperatorFunction<T, R>): MonoTypeOperatorFunction<T> | OperatorFunction<T, R> {
-  return selector
-    ? connect({
-        connector: () => new Subject<T>(),
-        setup: selector,
-      })
-    : multicast(new Subject<T>());
+  return selector ? connect(selector) : multicast(new Subject<T>());
 }
diff --git a/src/internal/operators/publishReplay.ts b/src/internal/operators/publishReplay.ts
index ada208dd16..6e2aa5c33f 100644
--- a/src/internal/operators/publishReplay.ts
+++ b/src/internal/operators/publishReplay.ts
@@ -39,7 +39,7 @@ export function publishReplay<T>(
  * @param timestampProvider The timestamp provider for the underlying {@link ReplaySubject}.
  * @deprecated To be removed in version 8. Use the new {@link connect} operator.
  * `source.pipe(publishReplay(size, window, fn, scheduler))` is equivalent to
- * `const subject = new ReplaySubject(size, window, scheduler), connect({ connector: () => subject, setup: fn })`.
+ * `const subject = new ReplaySubject(size, window, scheduler), source.pipe(connect(fn, { connector: () => subject }))`.
  */
 export function publishReplay<T, O extends ObservableInput<any>>(
   bufferSize: number | undefined,
diff --git a/src/internal/operators/share.ts b/src/internal/operators/share.ts
index 671bfc12f4..23711b11b1 100644
--- a/src/internal/operators/share.ts
+++ b/src/internal/operators/share.ts
@@ -7,7 +7,7 @@ import { Subscription } from '../Subscription';
 import { from } from '../observable/from';
 import { operate } from '../util/lift';
 
-interface ShareOptions<T, R> {
+export interface ShareConfig<T> {
   /**
    * The factory used to create the subject that will connect the source observable to
    * multicast consumers.
@@ -43,7 +43,7 @@ interface ShareOptions<T, R> {
 
 export function share<T>(): MonoTypeOperatorFunction<T>;
 
-export function share<T, R = T>(options: ShareOptions<T, R>): OperatorFunction<T, R>;
+export function share<T>(options: ShareConfig<T>): MonoTypeOperatorFunction<T>;
 
 /**
  * Returns a new Observable that multicasts (shares) the original Observable. As long as there is at least one
@@ -87,7 +87,7 @@ export function share<T, R = T>(options: ShareOptions<T, R>): OperatorFunction<T
  * // ... and so on
  * ```
  */
-export function share<T, R>(options?: ShareOptions<T, R>): OperatorFunction<T, T | R> {
+export function share<T>(options?: ShareConfig<T>): OperatorFunction<T, T> {
   options = options || {};
   const { connector = () => new Subject<T>(), resetOnComplete = true, resetOnError = true, resetOnRefCountZero = true } = options;
 
diff --git a/src/internal/types.ts b/src/internal/types.ts
index 851916a740..42b651ad77 100644
--- a/src/internal/types.ts
+++ b/src/internal/types.ts
@@ -87,7 +87,7 @@ export type SubscribableOrPromise<T> = Subscribable<T> | Subscribable<never> | P
 /** OBSERVABLE INTERFACES */
 
 export interface Subscribable<T> {
-  subscribe(observer: Observer<T>): Unsubscribable;
+  subscribe(observer: Partial<Observer<T>>): Unsubscribable;
 }
 
 /**
@@ -172,7 +172,7 @@ export interface Observer<T> {
   complete: () => void;
 }
 
-export type SubjectLike<T> = Observer<T> & Subscribable<T>;
+export interface SubjectLike<T> extends Observer<T>, Subscribable<T> {}
 
 /** SCHEDULER INTERFACES */