diff --git a/src/cdk/a11y/key-manager/tree-key-manager.spec.ts b/src/cdk/a11y/key-manager/tree-key-manager.spec.ts
index 77a89d78e139..338aead9c0e4 100644
--- a/src/cdk/a11y/key-manager/tree-key-manager.spec.ts
+++ b/src/cdk/a11y/key-manager/tree-key-manager.spec.ts
@@ -182,18 +182,8 @@ describe('TreeKeyManager', () => {
           itemList.notifyOnChanges();
         });
 
-        it('does not initialize with the first item activated', () => {
-          expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(-1);
-        });
-
-        it('if an item is subsequently enabled, activates it', () => {
-          itemList.reset([
-            new itemParam.constructor('Bilbo', true),
-            new itemParam.constructor('Frodo', false),
-            new itemParam.constructor('Pippin', true),
-          ]);
-          itemList.notifyOnChanges();
-          expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(1);
+        it('initializes with the first item activated', () => {
+          expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(0);
         });
       });
 
diff --git a/src/cdk/a11y/key-manager/tree-key-manager.ts b/src/cdk/a11y/key-manager/tree-key-manager.ts
index 81323e40ca35..c3d1fd683e0f 100644
--- a/src/cdk/a11y/key-manager/tree-key-manager.ts
+++ b/src/cdk/a11y/key-manager/tree-key-manager.ts
@@ -73,7 +73,7 @@ export class TreeKeyManager<T extends TreeKeyManagerItem> implements TreeKeyMana
       return;
     }
 
-    let focusIndex = -1;
+    let focusIndex = 0;
     for (let i = 0; i < this._items.length; i++) {
       if (!this._skipPredicateFn(this._items[i]) && !this._isItemDisabled(this._items[i])) {
         focusIndex = i;
@@ -81,10 +81,6 @@ export class TreeKeyManager<T extends TreeKeyManagerItem> implements TreeKeyMana
       }
     }
 
-    if (focusIndex === -1) {
-      return;
-    }
-
     this.focusItem(focusIndex);
     this._hasInitialFocused = true;
   }