United went ahead in the 34th minute at Old Trafford when Darren Fletcher smacked a swerving half-volley into the top left corner and doubled their tally in the 67th through Michael Carrick.
Antonio Valencia made it 3-0 with a deflected shot in the 76th after the ball was laid on by Paul Scholes.
"The second goal put us in the comfort zone and from there on I didn't think we could possibly lose it," United manager Alex Ferguson told ESPN television.
"If we get to the New Year within a point, or a point ahead, or level, then we have a great chance (to win the title) in the second half of the season."
Published 22 November 2009, 16:47 IST