Manchester United boss Sir Alex Ferguson is fearful of AC Milan's striker David Beckham's performance at Old Trafford, as he knows the capabilities of the ace midfielder very well.

Ferguson was less than complimentary about Beckham in the aftermath of United's 3-2 win in the first leg of their Champions League round-of-16 tie at San Siro last month.

But Ferguson is mindful of Beckham's almost unnerving habit of making fairytales come true, and was more generous in his assessment of the England ace, The Times reports.

"It is difficult to say what effect David will have on the tie because we don't know whether he is going to start, but the one thing with him that you have to be aware of is his delivery of the ball, it's fantastic," Ferguson said.

"I think David's strength has always been his crossing and his set-piece play, that doesn't change, and if he plays, that will be the threat against us," he said.

Beckham was mobbed upon his arrival at Manchester airport on Tuesday and is all set to get a rapturous reception at Old Trafford.

Ferguson said that he had been concerned about Rooney's fitness but now it is for Leonardo to worry about the England forward.

"It's incredible to see the way he has developed and matured," the Milan coach said. "Maybe it has something to do with Cristiano Ronaldo leaving. He has had to step up." (ANI)