diff --git a/lib/ansible/runner/__init__.py b/lib/ansible/runner/__init__.py
index f91fad38cc..dbcb869ae2 100644
--- a/lib/ansible/runner/__init__.py
+++ b/lib/ansible/runner/__init__.py
@@ -346,6 +346,12 @@ class Runner(object):
         delegate['transport'] = this_info.get('ansible_connection', self.transport)
         delegate['sudo_pass'] = this_info.get('ansible_sudo_pass', self.sudo_pass)
 
+        # Last chance to get private_key_file from global variables.
+        # this is usefull if delegated host is not defined in the inventory
+        if delegate['private_key_file'] is None:
+            delegate['private_key_file'] = remote_inject.get(
+                'ansible_ssh_private_key_file', None)
+
         if delegate['private_key_file'] is not None:
             delegate['private_key_file'] = os.path.expanduser(delegate['private_key_file'])