WAYNE Rooney received a reminder to concentrate on what he is good at during Manchester United's Premier League victory over Birmingham. With Cristiano Ronaldo joining Real Madrid, Rooney has been promised a more central berth by Sir Alex Ferguson this season. The immediate response has been positive. Rooney followed his goal in last weekend's Community Shield by scoring his 99th for United to clinch all three points against Alex McLeish's newly-promoted side. Yet it seems old habits die hard. For even though Ferguson has told the 23-year-old to do his damage in central areas, he could not resist the temptation to saunter out to the wing at times in his quest to get on the ball. "He wants to be everywhere all the time," said United assistant manager Mike Phelan. "But we have 10 other good players on the field and sometimes he has to realise the place where he does his best work is the best place to be. Rooney performance "Wayne sometimes drifts around and there were instances of that against Birmingham. His overall performance was good but he needs to remember when we create chances he scores goals." It is just a gentle reminder that Rooney is not quite the finished article. The problem is one Fabio Capello combats with England by allowing Rooney to swap positions with Steven Gerrard. No such opportunity currently exists at United, where neither Nani nor new signing Antonio Valencia are sure enough of their own bearings to risk an experiment in which they end up being overshadowed. Nevertheless, Rooney has started the campaign in decent goalscoring form, even if he might have got himself into three figures on Sunday. "It could have been 100," he said. "I had a couple of chances but their keeper made some good saves. "Overall I am delighted with the goal and pleased we got the three points." How much more can Rooney improve? Have your say.