Wayne Rooney's success at Manchester United this season is down to one thing - hard work.

The star striker is in the form of his life but many in the United camp attribute that to the fact that he has never worked harder at his game.

First team coach Rene Meulensteen singled him out for special praise to Sir Alex when he begged the Dutchman to help him practice painstaking volley exercises with both feet.

The session went on long after Rooney's other team-mates had departed just a day after United played an exhausting Premier League clash against Aston Villa.

A club source told the News of the World: "Since Sir Alex set him the task of stepping out of Ronaldo's shadow, he hasn't looked back."

"I'm not surprised he took those two headers against Milan so well. He does extra training drills involving headers from lobbed balls at all angles.

"He knew he had to improve in the box if he was going to score more goals and it's definitely paying off."