United's top scorer thundered home a close-range volley and tucked away a neat finish after Antonio Valencia had caught Jay Spearing in possession, bagging the decisive pair within five minutes of half-time.
The champions might have done more from promising positions in a one-sided second period, and were given a nervy ending to the game when Luis Suarez tucked away a late consolation strike for the visitors.
Having watched his side roar back to take a point at Stamford Bridge last weekend, Sir Alex Ferguson made a solitary change to his starting line-up; bringing Paul Scholes into central midfield and shifting Ryan Giggs to the left flank at the expense of Ashley Young.
Of greater pre-match interest was the visitors' selection. Suarez started for the first time since receiving an eight-game ban for racially abusing Patrice Evra, and unexpectedly shunned the United skipper's offer of a pre-match handshake.
The two seemed destined for closer contact within 30 seconds of the first whistle, until Rio Ferdinand raced in to clear the loose ball and found himself trapped in their collision course. Having been clattered by his captain, Ferdinand received treatment before continuing.
The visitors' early approach centred around attacking Evra. Glen Johnson was a continual outlet, driving down the right flank wherever possible, and the right-back curled a left-footed effort just wide of David De Gea's