Roy Keane's 50th Manchester United goal capped an awesome individual performance against battling Birmingham and ensured the Red Devils again closed the gap on Premiership leaders Chelsea to eight points.

Five days after Keane had stood toe-to-toe with Patrick Vieira in defence of Gary Neville, the veteran Irishman once again proved just what an exceptional leader he is, galvanising a team that appeared to be suffering a pretty severe Highbury hangover.

After 55 minutes of prodding, pushing, cajoling and encouraging, all to no effect, Keane decided it was time for more direct action.

At 33, the midfielder may not be quite the goal threat of old but when he snapped on to Cristiano Ronaldo's short pass 35 yards out, the Birmingham defence might have opted for a different course of action instead of merely backing off and inviting him to shoot.

Before they realised the danger, Keane had broken into the box and driven a low shot into the bottom corner, his first United goal since November 2003 and one his contribution to a 12th win in 14 league games for the Red Devils totally deserved.

Wayne Rooney may be 38 goals and 14 years behind his captain but already he looks like having the same impact on the Old Trafford club and, although Birmingham's fire had been doused by Keane's efforts, the 19-year-old still found time to wrap up victory with a neat volley after Kenny Cunningham had sold Maik Taylor short with an ill-advised back pass.

The more pessimistic members of United's support needed no reminding that immediately after their team had brought Arsenal's magnificent 49-match unbeaten run to an end in October, they promptly lost at Portsmouth.

It is those kind of early season results, which include a goalless draw at St Andrews, that have left Sir Alex Ferguson's men so far behind Chelsea despite a recent run of 11 wins from 13 outings.

Ferguson was adamant Tuesday's momentous events would not be followed by a similar let-down, insisting the form and confidence of his team is far different now than it was four months ago.

With the notable exception of Keane, Ferguson's words appeared to fall on deaf ears.

There may have been only three changes from the Arsenal game, including the absence of Paul Scholes whose involvement was restricted to sitting alongside his son in the stand, but it was a shadow of the side that destroyed the Gunners' hopes of retaining their crown.

Rio Ferdinand and Rooney were both guilty of gifting Birmingham possession, offering the visitors increased encouragement as the first-half wore on.

Ironically, it was Ferdinand's long ball to the England striker which forced Taylor into his only meaningful stop of the opening period, a clawing effort that saw him push the England striker's precise header on a post.

Other than that, it was mostly huff and puff from the hosts as Ryan Giggs, Ronaldo and returning striker Louis Saha flitted in and out of the contest, looking good at times but having no noticeable impact on an obdurate Birmingham defence.

The visitors could hardly have claimed to be a major attacking force in the game but with Jermaine Pennant's speed capable of causing problems, they were at least a threat and in Pandiani possessed a potentially lethal predator.

He might have upset a few folk in the Second City with his unflattering comparison of Birmingham and Florence, but he balanced that out with a debut goal against Middlesbrough in midweek and had the man dubbed 'The Rifle' seen his bullet volley fly in just past the half-hour mark, the visiting supporters would have forgiven him anything.

As it was, it crashed back off the underside of the bar.

The intensity of United's attacking play increased after half-time but they were forced to endure 10 more minutes of frustration before Keane made his decisive intervention.

Rooney may have joined his captain on the scoresheet with his well-taken volley after Taylor had been unable to get a firm contact on Cunningham's weak pass but in a way it was an injustice.

Teams:

Man Utd: Carroll, Gary Neville, Ferdinand, Brown, Heinze, Ronaldo, O'Shea, Keane, Giggs (Phil Neville 82), Rooney (Miller 82), Saha (Fortune 68).

Subs Not Used: Howard, Bellion.

Booked: Heinze.

Goals: Keane 55, Rooney 78.

Birmingham: Maik Taylor, Melchiot, Cunningham, Martin Taylor (Tebily 81), Clapham, Pennant, Nafti (Carter 72), Johnson, Gray, Pandiani, Blake (Morrison 72).

Subs Not Used: Kuqi, Vaesen.

Booked: Johnson, Nafti, Pennant.

Att: 67,838

Ref: D Gallagher (Oxfordshire).