Sir Alex was pleased to see Shinji Kagawa back in action after two months out injured and he was full of praise for fellow summer signing van Persie who once again stole the headlines with a stunning late strike.
"Robin is a fantastic player. He came on and changed the game for us. Every time the ball went to him he got hold of it and he did really well for us," added the manager.
"Shinji did very well in the first half. Obviously you expect him to tire with it being his first game for a couple of months and at that point we brought Robin on. I'm very pleased with Shinji - he did his job very well and he worked very hard in the early parts of the game."