diff --git a/django/db/models/deletion.py b/django/db/models/deletion.py
index 92fe4affb9..883c09ef83 100644
--- a/django/db/models/deletion.py
+++ b/django/db/models/deletion.py
@@ -277,6 +277,8 @@ class Collector:
             if self.can_fast_delete(instance):
                 with transaction.mark_for_rollback_on_error():
                     count = sql.DeleteQuery(model).delete_batch([instance.pk], self.using)
+                # Set primary key to None
+                setattr(instance, model._meta.pk.attname, None)
                 return count, {model._meta.label: count}
 
         with transaction.atomic(using=self.using, savepoint=False):