Sir Alex Ferguson said United would take things one game at a time after Ryan Giggs' goal sealed the win at QPR that put his side 15 points clear at the top of the table.
Rafael's wonderful first-half drive and Giggs' strike 10 minutes from time helped United secure a comfortable 2-0 victory over the bottom club.
"It is a good position, but you know the way we approach it is to win our next game,'' Ferguson told MUTV. "That is the best way to do it - carry on doing that.
"I think it was more about determination and concentration at the back, in particular. We defended that part very, very well. It was a scrappy game at times and the pitch was lively.
"It is a tight ground and it was an ideal situation for a shock. Fortunately, we didn't get that.
"One goal is never enough, as you know. It only takes a second to lose a goal. We created some good chances, but obviously Ryan's goal with 11 or 12 minutes to go killed the game."
The only negative was an injury to Robin van Persie, who was replaced late in the first half with a hip problem.
"He collided with a camera," Ferguson said. "It seems he hit the base of it, and he has got a very bruised hip."
The manager praised Rafael, who struck a superb opener, saying: "He has three goals for us this season. The lad has had an absolutely magnificent season and is maturing all the time. He has had a fantastic game."
His QPR counterpart Harry Redknapp remained defiant, saying he still believed Rangers - seven points adrift of safety - could survive.
"I thought we were bang in the game,'' he said. "This leaves us bottom today, but we won't be bottom at the end of the season. I still feel we'll get out of it.
"You probably think I'm mad, but I don't think I am. Everybody else has written us off, but I haven't. I still feel we have a chance."