Wayne Rooney scored to ensure Manchester United began the defence of their Premier League title with a 1-0 win over Birmingham at Old Trafford.

Rooney got off to the perfect start in his new central role, climbing highest to meet Nani's 34th-minute cross, then finishing off when his header bounced back off a post.

Joe Hart had made a terrific early stop to keep out Rooney's curling effort but he could only watch as the England striker put United ahead.

Gregory Vignal had a header cleared off the line by Evra before half-time but Rooney almost doubled United's lead a minute into the second period with a long-range effort that Hart did well to keep out.

Cristian Benitez went close after coming on while Michael Owen, another substitute, was twice denied a late debut goal firstly by the offside flag and then by the feet of Hart.