Wayne Rooney gave United the perfect start in the search for an unprecedented fourth league title in a row.
The Reds’ number ten scored the decisive goal, made life difficult for Birmingham all afternoon and might have had a hat-trick against a lesser goalkeeper than Joe Hart.
It wasn’t all plain sailing for the champions, however, and had Hart’s opposite number Ben Foster not pulled off a wonderful save of his own from Christian Benitez, the game might have ended all-square – just like the opening days of 2007 and 2008.
Sir Alex Ferguson fielded new signing Antonio Valencia on the right and the Ecuadorian made a confident start on United’s right flank, not least when he vaulted over a lunge by Birmingham left-back Gregory Vignal and whipped in an early cross.
The home fans were on their feet when Dimitar Berbatov was wrestled to the ground by Stephen Carr on the edge of the box – unpunished by referee Lee Mason. At the other end, James McFadden almost made matters worse with a curling shot just past the post as United’s defenders backed off.
Berbatov almost gained his revenge with a shot that Birmingham goalkeeper Joe Hart just managed to divert and when the ball broke to Nani from Rooney tussling with the centre-halves, the Blues managed to block the Portuguese’s shot and eventually clear their lines.
Hart, hailed as England’s number one by the away fans, made a picture-book save to thwart the next attack as Rooney tried to beat him with an exquisite chip. The Blues keeper, on loan from Manchester City, flicked the ball