Fergie not celebrating yet

Sir Alex Ferguson insists Manchester United's Barclays Premier League title defence could yet unravel.

United occupy a seemingly unassailable position at the summit, with nearest rivals Chelsea trailing by five points with four matches remaining following a 1-1 draw with Wigan on Monday.

But Ferguson is refusing to open the champagne just yet and said: "Wigan holding Chelsea puts us in a good position but in my experience in life you don't take things for granted."

He added: "We've got some difficult games ahead - Blackburn, West Ham, Chelsea and Wigan. We have three away games and one at home so we have to do a job.

"Because we have difficult games left, there is still a lot to play for and it could still go down to the wire.

"We could lose to Chelsea and we could lose all our remaining games. It's a very difficult league these days."

United have been ruthless this season, scoring 19 more times than Chelsea for a superior goal difference that is worth virtually a point.

Winger Cristiano Ronaldo has led the charge with a stunning 38-goal haul and Ferguson claims United's ambition deserves the return.

"One of the encouraging things is the goal difference is helping us," he said.

"That's deserved because we've attacked all season and have put an attacking emphasis on our game."