Sir Alex Ferguson has backed Japan playmaker Shinji Kagawa and Robin van Persie to carry Manchester United's attack while Wayne Rooney is out of action for the next four weeks.

Rooney was stretchered off in the closing stages of United's 3-2 win over Fulham at Old Trafford on Saturday and needed hospital treatment to stem the bleeding from a deep gash to his thigh suffered in a challenge with Hugo Rodallega.

The injury, which rules Rooney out of England's World Cup qualifiers against Moldova and Ukraine, leaves Ferguson without his star striker for Premier League clashes against Wigan, Southampton and Liverpool, as well as the club's opening Champions League group stage fixture.

But the United manager is hopeful that Kagawa, a £17 million signing from Borussia Dortmund, and van Persie, a £24 million capture from Arsenal, can prove more than adequate replacements for Rooney after marking their maiden appearances at Old Trafford with first half goals against Fulham.

Ferguson believes their partnership showed enough promising signs to hint at better things to come and he said: "It was fine. There will be a better understanding as time goes on but I was pleased with that.

"We normally play with one behind, whether it's Wayne that plays in that role, Danny Welbeck can do it, Ashley Young and Ryan Giggs can play there. We've got options that way."

Ferguson admits Rooney's absence will be a blow but the United star had actually started the day on the bench after being dropped following a lacklustre display in the 1-0 defeat at Everton.

"It looked a really bad one and he's gone to hospital obviously and it looks as if he'll be out for four weeks," Ferguson said.

"I don't know what happened, I think the player must have followed through with his shot."

While Ferguson was happy with his combination up front, he was more concerned with the way United allowed Fulham to score twice in sloppy fashion.

Damien Duff got in to easily to score Fulham's first in the third minute and Nemanja Vidic's own goal after a flap by David De Gea gave the visitors hope following van Persie, Kagawa and Rafael da Silva's first half strikes for United.

"You saw two sides of Manchester United in this match," Ferguson said. "It was cruise control but we made a terrible mistake for the second goal and it becomes a match when it should never have been.

"Some of the football was fantastic but after that we struggled."

At least van Persie got off to a flying start and the United star was relieved to have broken his duck for his new club.

"It was a good goal, a difficult goal, but it was a good cross from Patrice Evra," he said.

"The ball bounced just before it came to me, so I had to time it well and I did. It was a tight angle, but luckily it went in."

Fulham manager Martin Jol again left Clint Dempsey out of his squad after reporting Liverpool to the Premier League over claims of an illegal approach.

But Jol is confident the United States international will be willing to play again if he remains at the club beyond Friday's transfer deadline.

"I would have liked to have talked with him every day to tell him there are no bids," Jol said.

"You look at (Steven) Fletcher and (Matt) Jarvis and they both played for Wolves and then moved and I would have liked that if he was going to move.

"We could sit down if there was a bid and talk about it but there was no official bid so it is a very bad situation for us.

"I haven't seen him much but if no-one comes we can't send him to a non-league team or send him on loan to Stevenage. We will have to keep him, sit down with him but maybe something will happen this week."