IF MANCHESTER UNITED have been less than convincing in the early stages of their defence of the Premier League title, this performance provided promise of the strength and style still to come.

Wayne Rooney was brilliant, delivering a world-class goal that finally broke the deadlock in the second half and setting up Cristiano Ronaldo and substitute Nani for two more, with Dimitar Berbatov scoring his first Premier League goal for the club in between. It was almost vintage stuff.

Yet the game presented a microcosm of United’s season so far, for they were flat and anxious for much of the first half before Ronaldo and Rooney combined effectively on the edge of the area and Rooney fired a low shot past Scott Carson, the West Bromwich Albion goalkeeper. Referee Mark Halsey penalised Rooney for the manner in which he challenged Gianni Zuiverloon before setting up his strike, which seemed to ignite Rooney and his teammates. The longer the match went on the better they became, which Sir Alex Ferguson is sure will be the story of the season.

“The players have now got the legs to play 90 minutes and the rhythm and tempo as well. The speed of our game was terrific today,” said the Manchester United manager. “That was our best 90 minutes of the season. I reckon we are back on track and playing more like the real Manchester United.”

With free-scoring Chelsea having thrown down the gauntlet early in the day and Liverpool rising to the challenge against Wigan, it was imperative for United to demonstrate their ability and willingness to join the fight. They struggled early on, Ronaldo remaining a marginal influence until the second half and Berbatov unable to make any real impact before his pass sent Rooney on his way for the opening goal. The way he held up the ball before laying it off to Rooney, who crossed to Nani for the final goal, emphasised his class and it is a matter of time before the Bulgarian becomes a more consistently effective threat.

With Carlos Tevez and Anderson omitted Ferguson deployed a fluid and attacking midfield in support of the two strikers. Ronaldo and Park Ji-Sung switched flanks seamlessly and took up positions as part of a front four as frequently as they operated in midfield. But with Paul Scholes, Michael Carrick, Owen Hargreaves and Anderson absent, United appeared to lack solidity in midfield in the opening skirmishes, leaving themselves exposed to West Brom’s counter-attacks. When Darren Fletcher missed a tackle, allowing Robert Koren to set up Chris Brunt for a long-range shot, this became apparent, but Brunt’s effort was too close to Edwin van der Sar. Alas, it was as close as West Brom would come to springing an upset.

Inevitably, United’s movement and passing improved. Ronaldo manoeuvred his way through on the left side of the box to strike a shot that Carson saved and the Baggies keeper had to be alert again when Ryan Giggs’s free kick into the near post was headed goalwards by Rooney, Carson managing to parry the ball away.

Increasingly, the visitors found themselves pinned in their own half. A strong shout for a penalty was dismissed by referee Mark Halsey when Paul Robinson appeared to handle the ball but, from the resultant corner by Rooney, Nemanja Vidic’s header was saved by Carson’s legs.

West Brom rarely troubled their hosts but they worked hard and their defenders, especially Robinson and Jonas Olsson, were brave and obstinate, while Carson performed admirably. But Rooney, who has scored eight goals for club and country in his past six games, would not be denied and his goal, when it finally arrived, would have been worthy of winning the game.

He collected Berbatov’s pass, checked his run superbly when he entered the penalty box and cut inside to beat Ryan Donk before shooting past Carson into the bottom right corner. It signalled the end of West Brom’s resistance. Ronaldo and Berbatov were able to make them pay as United went some way towards addressing their goal difference behind Chelsea.

Rooney released Ronaldo on the edge of the area the Portuguese coolly stroked the ball between the goalkeeper’s legs. Two minutes later Nani crossed from the left and Berbatov met the ball with a sublime right-footed volley. Nani scored a fourth goal with a good finish from a ball supplied by the man of the moment.

“They paid £30m for Rooney but what is he worth now? £100m? I don’t know,” said Tony Mowbray, the West Brom manager.

MANCHESTER UNITED:Van der Sar 6, R Da Silva 7 (Neville 65min), Ferdinand 7, Vidic 7, Evra 6 (O’Shea 36min, 6), Ronaldo 6, Fletcher 7, Giggs 7, Park 6 (Nani 70min), Rooney 9, Berbatov 7

WEST BROMWICH ALBION: Carson 7, Zuiverloon 6, Donk 5, Olsson 7, Robinson 6, Morrison 5, Koren 6 (Moore 72min), Borja Valero 5, Greening 6, Brunt 5, Bednar 5 (Miller 53min, 5) Rooney56,Ronaldo69, Berbatov 71, Nani 90

Star man:Wayne Rooney (Manchester United)

Yellow card:West Brom: Zuiverloon