FA to probe United's behaviour

"What Roy did that night was incredible," said Ferguson. "It was an example of almost inhuman tolerance and mental strength.

"I hope we have more than one key player tomorrow, though, because this is the hardest task we have ever faced - and Milan know it."

Ruud van Nistelrooy, scorer of 36 Champions League goals in 38 appearances, is certain to start just two-and-a-half games back from an Achilles injury.

"All the goals I have scored are in the past," he said. "My career is all about what I produce now and the Milan game is definitely one of those occasions where scoring would represent my best goal."

Van Nistelrooy, along with Cristiano Ronaldo and Wayne Rooney, is the major reason why Ferguson rates this side better than the one containing David Beckham, Andy Cole and Dwight Yorke that strode to the unprecedented Treble success six years ago.

"It is hard to look at those - Ruud, Cristiano and Wayne - and compare them with anyone," said Ferguson. "That is what sways it for me."

AC Milan coach Carlo Ancelotti is set to play the same 4-3-2-1 formation he used at Old Trafford, with Jaap Stam likely to partner Alessandro Nesta in central defence and captain Paolo Maldini moving to left-back.

Andriy Shevchenko misses out again through injury, so Kaka and Rui Costa are likely to support Hernan Crespo in attack.

Despite leading the tie 1-0, Ancelotti has warned his side against complacency. "We cannot think of the first-leg result," he said. "We have to go out with the belief we can repeat our display at Old Trafford.

"I don't think either side will create a lot of chances and we certainly need to start playing with more speed in the final stages.

"United have put a lot of focus on this competition. That can be a positive thing but it can also be negative because their entire season depends on it.

"We have to go into this game with the right spirit. It is a big game and I know we can repeat our good display from the first leg."