Wayne Rooney continued his scoring spree to inspire Manchester United to a clinical victory over West Bromwich Albion.

Cristiano Ronaldo and Dimitar Berbatov also found the net during a devastating 15-minute period for the Barclays Premier League champions, with Nani completing the scoring in the last minute.

But it was a struggle until man-of-the-match Rooney broke the Baggies' resistance by scoring in his fifth successive match, a run that has yielded six goals for club and country and has now moved United into the top four.

West Brom had every reason to be fearful and it appeared those worries were proved valid when the England striker tucked home midway through the opening period.

On first viewing, Rooney appeared merely to use his strength to push Gianni Zuiverloon to one side as he skipped onto Ronaldo's through ball.

He then stepped inside Ryan Donk before beating Scott Carson from 10 yards. Television replays did not cast that much doubt on Rooney's challenge either but referee Mark Halsey thought otherwise and disallowed the goal for a push.

It was the most notable moment of a frustrating half for the hosts, who dominated possession but failed to break a stoic West Brom defence in which Donk and central defensive partner Jonas Olsson were superb.

Rooney did have a near-post header pushed away by Carson just after the one Halsey wiped out but other than that, it was just a succession of near-misses.

Ronaldo blasted a couple of free-kicks, one from fully 35 yards, into the wall and Darren Fletcher fired over from the edge of the area.

Rooney, who had taken on corner kick duties, dropped two into the area without anyone getting a touch and Rio Ferdinand had a penalty appeal turned down.

If that was not bad enough, United lost Patrice Evra nine minutes before the break with an injury which must make him a doubt for Tuesday's Champions League duel with Celtic.

The general zip that had been missing from United's play in the first half did not instantly reappear after the break.

There were still moments of excellence as Rooney warmed Carson's fingers from 25 yards and Berbatov brought another decent save from West Brom's sure-footed goalkeeper.

But United needed something special, which is exactly what Rooney is delivering at present.

There was still plenty of work to do when Berbatov slipped a pass to his right.

But Rooney darted into the box before stepping inside Donk onto his favoured right foot, with which he beat Carson at his near post. The relief was obvious as Rooney bellowed in celebration.

Carson won the next round of what was turning into a private battle, getting down low to steer away Rooney's shot after the England man had collected Ryan Giggs' pass.

The introduction of Gary Neville for Rafael da Silva shortly afterwards hinted at a cautious approach. Within five minutes, they had scored twice more.

First Rooney, having got his goal, turned provider to send Ronaldo flying through. It is not the kind of opportunity a prospective world player of the year passes up.

Then substitute Nani saw his low cross bounce through the penalty area to Berbatov who calmly leant back and smashed his first Premier League goal for United - and his first of any kind at Old Trafford - past the helpless Carson.

Giggs tried to get his name on the scoresheet and Rooney went close again before his unselfish streak allowed him to claim another assist as he rolled an inviting pass across goal to Nani.