their work-rate and brought on a couple of energetic substitutes.
Rickie Lambert had a volley well held by De Gea before cracking another attempt wide following an error by Chris Smalling. A casual pass by Kagawa was picked up by his fellow countryman Maya Yoshida and, when Smalling headed out the centre, substitute Steve Davis dragged his shot off target.
The lethargy brought the boss down to the touchline but the chances kept coming at De Gea's end. The Spanish shot-stopper gobbled up a Lambert free-kick at the second attempt while Davis nodded over the top as the pressure was maintained.
Sir Alex obviously felt it was time to introduce a calm head, replacing Smalling with Rio Ferdinand, in an attempt to steady the ship. At least Rooney mustered a first noteworthy effort of the second half on 71 minutes but his shot lacked the power to beat Boruc after being picked out by strike-partner van Persie.
Nani joined another substitute, Rafael, on the field with Jones reverting to midfield as United desperately sought to regain some energy and sparkle. Nani was quickly involved with van Persie unable to convert his cross due to a brilliant stop by Boruc and, when the Dutchman did find the net from a Rooney centre soon afterwards, he was flagged offside.