WAYNE ROONEY was KO’d by a horror injury yesterday — and could even be sold for £50million if he does not shape up.

Roo horror KO rocks England ... but it's his attitude that puts Utd future in doubt

The Sun understands Manchester United’s patience has been stretched to the limit by Roo’s behaviour on and off the pitch.

Now the club would consider selling him for £50m if they do not see an improvement.

The England striker was left on the bench for the 3-2 win over Fulham and only came on after 68 minutes.

But he was soon taken off on a stretcher with an ugly deep gash on his right thigh after an accidental clash with Hugo Rodellega.

United boss Alex Ferguson confirmed Rooney will now be out for at least four weeks.

That rules him out of England’s double World Cup qualifiers against Moldova and Ukraine next month.

Ferguson’s programme notes yesterday contained a significant sentence.

After explaining how impressed he had been by new signing Robin van Persie’s desire to play for United, Fergie added: “If I hear a player has fallen out of love with us, and is looking elsewhere I invariably help them out of the door.”

Rooney was poor in Monday’s 1-0 defeat at Everton and Ferguson is understood to be unhappy with his fitness levels.

But the club were concerned about Rooney’s form, fitness and off field behaviour even before he returned for pre-season training — and discussions were held at boardroom level.

His desperate day yesterday ended on a stretcher and an ambulance to hospital after he jumped to block a Rodallega shot in injury time — and the Fulham player landed on him.

Fergie said: “It is a very bad one. He has gone to hospital but it looks as if he could be out for four weeks.

“I don’t know what happened. I think the player must have followed through after his shot and he’s got a bad one. It was an accident.”

Fulham chief Martin Jol admitted he was stunned to see Rooney dumped on the bench.

He said: “I was surprised. I thought Van Persie and Rooney would play.

“I know Kagawa from my time in Germany and I knew he would not play on the left. I thought it might have been an advantage because my players did not know him.

“He is a quality player. But Rooney is a fantastic player as well.”

Fergie was unhappy at the way his team let Fulham back into the game after a Nemanja Vidic mistake on a day Van Persie marked his full debut with a wonder goal.

Fergie said: “You saw two sides of United. It was cruise control but a terrible mistake for the second goal and it becomes a match and it should never have been a match.”

On Van Persie’s goal Ferguson added: “It was a fantastic finish, absolutely brilliant.”