Javier 'Chicharito' Hernandez came off the bench to clinch United's second league away win of the season and give the Reds the happiest of starts to the New Year.
The Mexican's 75th-minute header, added to a third-minute goal from Wayne Rooney, ensured all three points for the league leaders who survived a major scare when Peter Odemwingie missed a penalty for West Brom just after the hour mark when the score was 1-1. The Baggies had earlier cancelled out Rooney's opener with a stunning long-range strike from midfielder James Morrison.
The only worry for United as the game drew to a close was an apparent injury to Rooney but with Sir Alex having used all three subs, the striker played on to the final whistle. Wayne limped during the final moments but there was nothing wrong with his movement at the opposite end of the match, when he made the breakthrough with the first Barclays Premier League goal of 2011.
It was also Rooney's first goal from open play this season - his last was away to Bayern Munich in March. Two Frenchmen combined to create it for the England striker - Gabriel Obertan, making his first league start away from Old Trafford, drew the attention of two West Brom defenders with some trickery on the left flank and then rolled the ball back for Patrice Evra to whip in a first-time cross. Rooney met it ten yards out and although his downward header lacked power, the ball bounced off the turf and beyond Scott Carson’s despairing dive to United’s surprise and delight.
West Brom refused to be bowed by this early blow, however, and eleven minutes later their positive approach to the game paid dividends. A long punt from the Baggies’ back line was headed away by Nemanja Vidic but