Manchester United boss Sir Alex Ferguson explained his tactical changes after victory over Norwich City.

A forgettable first half in which Norwich goalkeeper John Ruddy scarcely had a save to make prompted Sir Alex to make tactical tweaks at the break, and he feels these changes had a positive effect.

"We changed Ji-sung Park into a more central position, and Nani to the wide left position, to allow Antonio Valencia to get forward a bit more on the right. We improved a good bit, we had much more speed in our game and more control. In the second half we improved but we still hardly made any chances in the game because they were so deep. They had everyone in the penalty box, two midfield players sat in front of the back four. I've seen that before many times and it's very, very difficult to break down. We found that today.

"Norwich just stuck to their box and hit long balls and they got a few counter attacks out of that and caused us a few problems. In fact, they probably got something out of every counter-attack. That put us under pressure a lot. Norwich's counter-attacks could have hurt us."