diff --git a/pkg/controller/endpointslice/endpointslice_controller_test.go b/pkg/controller/endpointslice/endpointslice_controller_test.go
index a8fda60bba321..59daac8594907 100644
--- a/pkg/controller/endpointslice/endpointslice_controller_test.go
+++ b/pkg/controller/endpointslice/endpointslice_controller_test.go
@@ -33,6 +33,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/intstr"
+	"k8s.io/apimachinery/pkg/util/rand"
 	"k8s.io/apimachinery/pkg/util/wait"
 	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	"k8s.io/client-go/informers"
@@ -61,7 +62,8 @@ type endpointSliceController struct {
 }
 
 func newController(nodeNames []string, batchPeriod time.Duration) (*fake.Clientset, *endpointSliceController) {
-	client := newClientset()
+	client := fake.NewSimpleClientset()
+
 	informerFactory := informers.NewSharedInformerFactory(client, controller.NoResyncPeriodFunc())
 	nodeInformer := informerFactory.Core().V1().Nodes()
 	indexer := nodeInformer.Informer().GetIndexer()
@@ -69,11 +71,36 @@ func newController(nodeNames []string, batchPeriod time.Duration) (*fake.Clients
 		indexer.Add(&v1.Node{ObjectMeta: metav1.ObjectMeta{Name: nodeName}})
 	}
 
+	esInformer := informerFactory.Discovery().V1().EndpointSlices()
+	esIndexer := esInformer.Informer().GetIndexer()
+
+	// These reactors are required to mock functionality that would be covered
+	// automatically if we weren't using the fake client.
+	client.PrependReactor("create", "endpointslices", k8stesting.ReactionFunc(func(action k8stesting.Action) (bool, runtime.Object, error) {
+		endpointSlice := action.(k8stesting.CreateAction).GetObject().(*discovery.EndpointSlice)
+
+		if endpointSlice.ObjectMeta.GenerateName != "" {
+			endpointSlice.ObjectMeta.Name = fmt.Sprintf("%s-%s", endpointSlice.ObjectMeta.GenerateName, rand.String(8))
+			endpointSlice.ObjectMeta.GenerateName = ""
+		}
+		endpointSlice.Generation = 1
+		esIndexer.Add(endpointSlice)
+
+		return false, endpointSlice, nil
+	}))
+	client.PrependReactor("update", "endpointslices", k8stesting.ReactionFunc(func(action k8stesting.Action) (bool, runtime.Object, error) {
+		endpointSlice := action.(k8stesting.CreateAction).GetObject().(*discovery.EndpointSlice)
+		endpointSlice.Generation++
+		esIndexer.Update(endpointSlice)
+
+		return false, endpointSlice, nil
+	}))
+
 	esController := NewController(
 		informerFactory.Core().V1().Pods(),
 		informerFactory.Core().V1().Services(),
 		nodeInformer,
-		informerFactory.Discovery().V1().EndpointSlices(),
+		esInformer,
 		int32(100),
 		client,
 		batchPeriod)
diff --git a/pkg/controller/endpointslice/endpointslice_tracker.go b/pkg/controller/endpointslice/endpointslice_tracker.go
index 0c213698b3d81..1c411b0a0f827 100644
--- a/pkg/controller/endpointslice/endpointslice_tracker.go
+++ b/pkg/controller/endpointslice/endpointslice_tracker.go
@@ -80,9 +80,12 @@ func (est *endpointSliceTracker) ShouldSync(endpointSlice *discovery.EndpointSli
 	return !ok || endpointSlice.Generation > g
 }
 
-// StaleSlices returns true if one or more of the provided EndpointSlices
-// have older generations than the corresponding tracked ones or if the tracker
-// is expecting one or more of the provided EndpointSlices to be deleted.
+// StaleSlices returns true if any of the following are true:
+// 1. One or more of the provided EndpointSlices have older generations than the
+//    corresponding tracked ones.
+// 2. The tracker is expecting one or more of the provided EndpointSlices to be
+//    deleted.
+// 3. The tracker is tracking EndpointSlices that have not been provided.
 func (est *endpointSliceTracker) StaleSlices(service *v1.Service, endpointSlices []*discovery.EndpointSlice) bool {
 	est.lock.Lock()
 	defer est.lock.Unlock()
@@ -92,12 +95,23 @@ func (est *endpointSliceTracker) StaleSlices(service *v1.Service, endpointSlices
 	if !ok {
 		return false
 	}
+	providedSlices := map[types.UID]int64{}
 	for _, endpointSlice := range endpointSlices {
+		providedSlices[endpointSlice.UID] = endpointSlice.Generation
 		g, ok := gfs[endpointSlice.UID]
 		if ok && (g == deletionExpected || g > endpointSlice.Generation) {
 			return true
 		}
 	}
+	for uid, generation := range gfs {
+		if generation == deletionExpected {
+			continue
+		}
+		_, ok := providedSlices[uid]
+		if !ok {
+			return true
+		}
+	}
 	return false
 }
 
diff --git a/pkg/controller/endpointslice/endpointslice_tracker_test.go b/pkg/controller/endpointslice/endpointslice_tracker_test.go
index c34a2c9c3c722..845b64db3cddd 100644
--- a/pkg/controller/endpointslice/endpointslice_tracker_test.go
+++ b/pkg/controller/endpointslice/endpointslice_tracker_test.go
@@ -184,6 +184,30 @@ func TestEndpointSliceTrackerStaleSlices(t *testing.T) {
 		serviceParam: &v1.Service{ObjectMeta: metav1.ObjectMeta{Name: "svc1", Namespace: "ns1"}},
 		slicesParam:  []*discovery.EndpointSlice{epSlice1NewerGen},
 		expectNewer:  false,
+	}, {
+		name: "slice in params is expected to be deleted",
+		tracker: &endpointSliceTracker{
+			generationsByService: map[types.NamespacedName]generationsBySlice{
+				{Name: "svc1", Namespace: "ns1"}: {
+					epSlice1.UID: deletionExpected,
+				},
+			},
+		},
+		serviceParam: &v1.Service{ObjectMeta: metav1.ObjectMeta{Name: "svc1", Namespace: "ns1"}},
+		slicesParam:  []*discovery.EndpointSlice{epSlice1},
+		expectNewer:  true,
+	}, {
+		name: "slice in tracker but not in params",
+		tracker: &endpointSliceTracker{
+			generationsByService: map[types.NamespacedName]generationsBySlice{
+				{Name: "svc1", Namespace: "ns1"}: {
+					epSlice1.UID: epSlice1.Generation,
+				},
+			},
+		},
+		serviceParam: &v1.Service{ObjectMeta: metav1.ObjectMeta{Name: "svc1", Namespace: "ns1"}},
+		slicesParam:  []*discovery.EndpointSlice{},
+		expectNewer:  true,
 	}}
 
 	for _, tc := range testCases {
diff --git a/pkg/controller/endpointslicemirroring/endpointslice_tracker.go b/pkg/controller/endpointslicemirroring/endpointslice_tracker.go
index 8fb440e7bfd4f..365c30d612b23 100644
--- a/pkg/controller/endpointslicemirroring/endpointslice_tracker.go
+++ b/pkg/controller/endpointslicemirroring/endpointslice_tracker.go
@@ -80,9 +80,12 @@ func (est *endpointSliceTracker) ShouldSync(endpointSlice *discovery.EndpointSli
 	return !ok || endpointSlice.Generation > g
 }
 
-// StaleSlices returns true if one or more of the provided EndpointSlices
-// have older generations than the corresponding tracked ones or if the tracker
-// is expecting one or more of the provided EndpointSlices to be deleted.
+// StaleSlices returns true if any of the following are true:
+// 1. One or more of the provided EndpointSlices have older generations than the
+//    corresponding tracked ones.
+// 2. The tracker is expecting one or more of the provided EndpointSlices to be
+//    deleted.
+// 3. The tracker is tracking EndpointSlices that have not been provided.
 func (est *endpointSliceTracker) StaleSlices(service *v1.Service, endpointSlices []*discovery.EndpointSlice) bool {
 	est.lock.Lock()
 	defer est.lock.Unlock()
@@ -92,12 +95,23 @@ func (est *endpointSliceTracker) StaleSlices(service *v1.Service, endpointSlices
 	if !ok {
 		return false
 	}
+	providedSlices := map[types.UID]int64{}
 	for _, endpointSlice := range endpointSlices {
+		providedSlices[endpointSlice.UID] = endpointSlice.Generation
 		g, ok := gfs[endpointSlice.UID]
 		if ok && (g == deletionExpected || g > endpointSlice.Generation) {
 			return true
 		}
 	}
+	for uid, generation := range gfs {
+		if generation == deletionExpected {
+			continue
+		}
+		_, ok := providedSlices[uid]
+		if !ok {
+			return true
+		}
+	}
 	return false
 }
 
diff --git a/pkg/controller/endpointslicemirroring/endpointslice_tracker_test.go b/pkg/controller/endpointslicemirroring/endpointslice_tracker_test.go
index 64ba4b3c4da49..40c1c8e06e6ce 100644
--- a/pkg/controller/endpointslicemirroring/endpointslice_tracker_test.go
+++ b/pkg/controller/endpointslicemirroring/endpointslice_tracker_test.go
@@ -184,6 +184,30 @@ func TestEndpointSliceTrackerStaleSlices(t *testing.T) {
 		serviceParam: &v1.Service{ObjectMeta: metav1.ObjectMeta{Name: "svc1", Namespace: "ns1"}},
 		slicesParam:  []*discovery.EndpointSlice{epSlice1NewerGen},
 		expectNewer:  false,
+	}, {
+		name: "slice in params is expected to be deleted",
+		tracker: &endpointSliceTracker{
+			generationsByService: map[types.NamespacedName]generationsBySlice{
+				{Name: "svc1", Namespace: "ns1"}: {
+					epSlice1.UID: deletionExpected,
+				},
+			},
+		},
+		serviceParam: &v1.Service{ObjectMeta: metav1.ObjectMeta{Name: "svc1", Namespace: "ns1"}},
+		slicesParam:  []*discovery.EndpointSlice{epSlice1},
+		expectNewer:  true,
+	}, {
+		name: "slice in tracker but not in params",
+		tracker: &endpointSliceTracker{
+			generationsByService: map[types.NamespacedName]generationsBySlice{
+				{Name: "svc1", Namespace: "ns1"}: {
+					epSlice1.UID: epSlice1.Generation,
+				},
+			},
+		},
+		serviceParam: &v1.Service{ObjectMeta: metav1.ObjectMeta{Name: "svc1", Namespace: "ns1"}},
+		slicesParam:  []*discovery.EndpointSlice{},
+		expectNewer:  true,
 	}}
 
 	for _, tc := range testCases {