David Moyes, the Manchester United manager, believes Wayne Rooney is already a club "legend" and has backed the striker to become United's all-time top scorer.

Rooney took third position on that particular list when he scored twice against West Ham United on Saturday.

That took the striker to 212 goals in 436 appearances, leaving him just 25 short of Denis Law and 37 shy of the man who tops the charts, Sir Bobby Charlton. When Rooney signed a new five-and-a-half-year contract last month, Moyes challenged him to become a great like Charlton and Law, but he believes the striker has already achieved that after 10 years at the club. "If you are third top scorer of a club like Manchester United you already are a legend," said Moyes.

"As long as he doesn't pick up any serious injuries he has a real good chance of breaking Denis Law's and Sir Bobby Charlton's [records] and that would be some feat."

Rooney's first strike at Upton Park is a strong contender for goal of the season. The United striker brushed off James Tomkins' challenge before lobbing West Ham goalkeeper Adrian from just inside the half-way line.

Moyes is looking for a similar performance from Rooney tonight when neighbours Manchester City head to Old Trafford with the title still firmly in their sights.

"I don't know if he'll be the key man because this game has got many top-class players in it, but he is certainly one of them," the Scot said. "His form throughout has been very good and his goal against West Ham capped it all off. He has a real appetite back again. On Saturday he showed what he is about. He has a big energy back again.

"Everyone who knew Wayne Rooney from old in his early days would say one of the biggest things [about him] was that he had big energy and a big heart. And if you get Wayne playing like that well the rest of his football takes care of itself."