A late own goal ensured Manchester United opened their title defence with a 2-1 win at West Bromwich Albion on Sunday, but another mistake from goalkeeper David de Gea and injuries to Rio Ferdinand and Nemanja Vidic marred an otherwise perfect start for manager Sir Alex Ferguson.
Wayne Rooney gave United the lead in the 13th minute, when the England international combined with Ashley Young before dispatching a left-footed shot beyond goalkeeper Ben Foster.
Shane Long equalised on his competitive debut for West Brom when his weak effort slipped under the body of de Gea. But United grabbed the winner when Young's cross deflected off West Brom defender Steven Reid and past Foster in the 81st minute.
United achieved what their main rivals failed this weekend, after Chelsea drew 0-0 at Stoke City on Sunday and Arsenal and Liverpool could also only draw their opening games on Saturday.
However, Ferguson was left to rue a "torrid few days" after Ferdinand and Vidic picked up injuries to join Rafael Da Silva in the United treatment room.
Ferguson is hopeful that Vidic, who has a recurrent calf problem, should be back within two weeks but Ferdinand, who limped off with a hamstring injury, will be side-lined for six weeks. Da Silva, meanwhile, will be out of action for 10 weeks after dislocating his shoulder.