MANCHESTER UNITED YAKAMILISHA USAJILI WA ZAHA KWA PAUNI MILIONI 15

Manchester United have clinched a £15million deal for Crystal Palace winger Wilfried Zaha... as it emerged Ashley Young will miss their Champions League double-header against Real Madrid with a knee problem. 

Young limped off in the 2-1 win over Liverpool on January 13 after a collision with Daniel Agger - and Sportsmail understands the winger has damaged his left medial ligament so will miss at least another four weeks. 

United manager Sir Alex Ferguson hoped to include Young in his squad to face Tottenham last weekend but the winger was ruled out after medical tests. 

Incoming: Wilfried Zaha will move to Manchester United but remain at Crystal Palace until the summer

Cat that got the cream: Sir Alex Ferguson has beaten many of his rivals to the signing

Young's club and England team-mate Wayne Rooney also gave United cause for some concern when he pulled up during training in the Middle East on Wednesday. 

Rooney recently missed three weeks with a knee problem and only returned to action in the FA Cup replay victory over West Ham a week ago. 

On Wednesday he was seen grimacing and holding his left thigh and it remains to be seen if the striker is in contention for this weekend's FA Cup fourth round clash with Fulham at Old Trafford. 

Young's prolonged stint on the sidelines will come as a major blow to United as they enter a crucial part of their season. 

The midfielder will definitely miss both legs of the Champions League second round clash against Jose Mourinho's Spanish giants Real. Young is also likely to be absent for the domestic fixtures against Fulham, Southampton, Everton, QPR, Norwich, West Ham and Reading. 

He will be unavailable for England's friendly against Brazil, but should be fit for the crucial March World Cup qualifying double header with San Marino and Montenegro.

In better news for Barclays Premier League leaders United, the protracted deal for Palace starlet Zaha has finally been agreed. 

United will pay £10million up front - the biggest down payment for a Championship player, exceeding the £6m Arsenal initially paid Southampton for 17-year-old Theo Walcott on in 2006.

Blow: Ashley Young has been ruled out for one month meaning he will miss the games against Real Madrid

The remaining £5m will be made up of various add-ons, £3m based on appearances, and the remaining £2m based on trophies and England appearances. 

Palace have also agreed a 10 per cent sell-on fee. Zaha will sign a five-and-a-half year contract at Old Trafford which will start at £35,000 a week, rising as he develops at the club. 

The England international will have a medical for United within the next 48 hours and will be loaned back to Palace for the remainder of the season - a key boost to Palace boss Ian Holloway as he strives to win promotion to the Premier League.