Dimitar Berbatov fired in his third hat-trick of the season as Manchester United cruised past Birmingham 5-0 in a one-sided encounter at Old Trafford.

The Bulgarian was at his stunning best as he made it 17 goals in 18 league starts to cement his place at the top of the English Premier League goal-scoring charts.

Veteran Ryan Giggs, who was as fresh and energetic as anyone on the pitch, and Nani got the others as United maintained their top-of-the-table form with their 11th win from 12 at home.

For Alex McLeish the future looks far more ominous. Sitting perilously close to the drop zone, Birmingham's normally solid defence were run ragged without the dependable Scott Dann, who has been ruled out for the season.

It took just 90 seconds for United to open the scoring. Nani won a corner after Liam Ridgewell dithered and from Giggs' dead-ball cross, John O'Shea flicked on for Berbatov to nod home from a yard out.

Ben Foster, who left Old Trafford in the summer, did well to keep out a Berbatov blast minutes later after the striker pounced on the keeper's miscued clearance.

The second finally came just after the half hour when Roger Johnson sloppily gave away the ball in his own half and Wayne Rooney worked the ball through to Berbatov to cut inside and smash in from eight yards out.

United added the third on the stroke of half-time when Berbatov intercepted David Bentley's cross-field pass and the ball ran to Rooney, whose low cross was fired in by an unmarked Giggs.

While Berbatov cannot stop scoring, his strike partner Rooney has scored just once from open play all season and the England man missed a sitter just after half-time - heading wide from two yards out.

But he had a big part in United's fourth in the 53rd minute. Rooney was the only man alert to Edwin van der Sar's long clearance and he gave the ball to Giggs, who crossed for Berbatov to fire in off the underside of the crossbar.

Birmingham had a golden opportunity to pull a goal back in the 57th minute but Keith Fahey miscontrolled the ball two yards out in front of an empty net.

Nani, who had a largely frustrating afternoon, added a fifth in the 76th minute when he cut inside and hit an 18-yard shot beyond Foster.