"It's been a great day for us and we've got a big chance (of winning the title)," Fergie said after the Hammers game.
"Getting the three points was the most important thing and to do that we had to endure quite a bit of pain and agony - especially when they scored and we went down to ten men.
"There were a few nervous moments before half-time, but thankfully we kept it at 3-1.
"We changed things around tactically to ensure that we kept possession in the second half.
"We're as good as anyone in the game at doing that when we keep our concentration and the fourth goal finished it for us.
"The game was marred by immaturity from Nani. He retaliated when he didn't need to and the referee didn't have any option but to send him off.
"Nevertheless, I'm sure he'll learn from it."