Manchester United boss Sir Alex Ferguson admits they targeted Arsenal's fullbacks for victory yesterday.

Johan Djourou was given such a torrid time out of position at right-back by Nani that he had to be substituted for 18-year-old Nico Yennaris at half-time.

The Gunners have struggled to fill the spaces left vacant by their injured full-backs in recent weeks and Ferguson admitted he was conscious that area could be exposed.

"That's been their problem for a few weeks, that is a disappointment for them without natural full-backs like Bacary Sagna and Kieran Gibbs," Ferguson said.

"They are playing centre-backs there so it is difficult for them. But they had only conceded six goals at home until today so they have not done a lot wrong in the defensive part. We had to play well and for most of the game we did.

"It was an amazing amount of chances we had, it's always difficult coming to here and Arsenal are a top side.

"We're a bit disappointed that we only scored twice. The first half in particular was a golden period for us, we should have rammed home the advantage.

"Then in the first 15 minutes of the second half they had three great chances and missed them all, so we rode our luck there. But we hit on the counter attack and through the game we had great chances."