diff --git a/django/core/apps/cache.py b/django/core/apps/cache.py
index e9a4215440..74488325a8 100644
--- a/django/core/apps/cache.py
+++ b/django/core/apps/cache.py
@@ -43,9 +43,6 @@ class AppCache(object):
         # Mapping of labels to AppConfig instances for installed apps.
         self.app_configs = OrderedDict()
 
-        # Pending lookups for lazy relations
-        self.pending_lookups = {}
-
         # Set of app names. Allows restricting the set of installed apps.
         # Used by TransactionTestCase.available_apps for performance reasons.
         self.available_apps = None
@@ -54,6 +51,9 @@ class AppCache(object):
         self._apps_loaded = not self.master
         self._models_loaded = not self.master
 
+        # Pending lookups for lazy relations.
+        self._pending_lookups = {}
+
         # Cache for get_models.
         self._get_models_cache = {}
 
diff --git a/django/db/models/fields/related.py b/django/db/models/fields/related.py
index 1b141af099..cf35504afe 100644
--- a/django/db/models/fields/related.py
+++ b/django/db/models/fields/related.py
@@ -74,7 +74,7 @@ def add_lazy_relation(cls, field, relation, operation):
     else:
         key = (app_label, model_name)
         value = (cls, field, operation)
-        cls._meta.app_cache.pending_lookups.setdefault(key, []).append(value)
+        cls._meta.app_cache._pending_lookups.setdefault(key, []).append(value)
 
 
 def do_pending_lookups(sender, **kwargs):
@@ -82,7 +82,7 @@ def do_pending_lookups(sender, **kwargs):
     Handle any pending relations to the sending model. Sent from class_prepared.
     """
     key = (sender._meta.app_label, sender.__name__)
-    for cls, field, operation in sender._meta.app_cache.pending_lookups.pop(key, []):
+    for cls, field, operation in sender._meta.app_cache._pending_lookups.pop(key, []):
         operation(field, sender, cls)
 
 signals.class_prepared.connect(do_pending_lookups)