Birmingham City 0 Manchester United 1: Manchester United continue to gather points without performances.

Alex Ferguson's team have won five consecutive Premier League games in which they have neither conceded a goal nor blinded opponents with brilliance. Sound goalkeeping, solid defending and the idiosyncratic ingenuity of Cristiano Ronaldo are keeping them at Arsenal's heels, but much of the old chemistry is missing.

Birmingham have not beaten United since November 1978 and were thwarted by a combination of Edwin van der Sar's saves and the support he enjoyed from his centre-backs, Rio Ferdinand and Nemanja Vidic.

Soon after half-time a lapse of concentration by Franck Queudrue, Birmingham's left-back, offered Ronaldo a chance he accepted astutely. By then Van der Sar, suffering from a damaged toe, had given way to Tomasz Kuszczak who proved equally adept at frustrating Birmingham's better scoring attempts. Ferguson fears that Van der Sar will miss tomorrow's Champions League match against Roma, but the Pole should be an adequate deputy if the way he kept out a shot from Gary McSheffrey that Ferdinand looked like heading into his own net was anything to go by.

Elsewhere in the United team, however, the options look confused. Up front Carlos Tevez resumed his partnership with Wayne Rooney but the best double acts thrive on contrasts of style and method and this pair are too alike to surprise defences with something unexpected; two Ernie Wises looking for the same punchline. When a Champions League fixture is coming up teams like to pace themselves at the weekend but tomorrow night Ryan Giggs, Paul Scholes and Michael Carrick will need to improve on Saturday's jaded displays.

Ferguson has confessed to being bewildered at United's continued failure to take chances at their usual prolific rate. Seven goals in eight Premier League matches is not exactly the stuff of legends and the waywardness of much of their finishing at St Andrews, particularly when Birmingham began to tire in the last half-hour, indicated a rare lack of confidence in finishing.

As a result Maik Taylor, the Birmingham goalkeeper, was underemployed compared to Van der Sar and Kuszczak. Midway through the first half a slick move involving Carrick, Giggs and Wes Brown set up Ronaldo for a shot which Taylor managed to block but by then Van der Sar had saved from Cameron Jerome and Queudrue, while Ferdinand had cleared a header from McSheffrey off the line. "We needed to take one of those chances," said Bruce afterwards. "In the first half we were lucky," Ferguson admitted, "and I couldn't wait to get in at half-time."

In the event Queudrue, in a quandary, came to the champions' aid. Ferdinand's vague heave upfield carried no threat as it reached the Birmingham penalty area but the French defender, facing his own goal as he met the ball, hesitated, seemingly unaware of the lurking Ronaldo who took possession and skilfully evaded Liam Ridgewell and Taylor before putting United ahead. "We made a horrible mistake and got punished," said Bruce. "To lose like that is cruel."

A lack of goals bedevilled Birmingham when they were relegated two seasons ago after scoring only 28 in 38 games. Like Manchester United they have scored only seven in eight this time but on Saturday were entitled to be encouraged by the number of opportunities they created.

The problem for Birmingham was that they set themselves a daunting pace from the outset and were never going to keep it up. Inevitably the spring went out of the excellent McSheffrey's step and once that happened they were reduced to trying to find Jerome with long balls which were easily dealt with by Ferdinand and Vidic.

If it was any consolation for Birmingham Ferguson described them as "the best side we have played this season. They were very athletic, very aggressive and very quick about the pitch and even at 1-0 I was still praying we would get through the match".

• Guardian Service