Manchester United v AC Milan - Milan line-up a puzzle for Sir Alex Ferguson

Broken bridges have been rebuilt by Ferguson and Beckham since their fractured relationship paved the way for the midfielder's £25 million transfer from United to Real Madrid in 2003, but Ferguson has yet to take the step of lavishing the kind of nostalgic praise on Beckham that he has reserved for his successor in the No 7 shirt – Cristiano Ronaldo – since the Portuguese winger's defection to Madrid last summer.

Ferguson might have rolled an eye and cast doubt publicly on Milan's decision to deploy Beckham as a central midfielder following United's 3-2 first-leg victory in the San Siro last month, but the Scot retains a healthy respect for the former England captain's continuing ability to hurt opponents with his peerless right boot. Wayne Rooney, rather than Beckham, is the man Ferguson expects to dominate the headlines in Wednesday's last 16, second-leg tie in Manchester.

But, like the boxer who is wary of the old slugger with the ferocious uppercut, Ferguson admits that Beckham retains the ability to deliver a knockout blow for Milan with the one component of his game that remains as potent now as it always has been.

Ferguson said: "I think David's strength has always been in his crossing and his set-piece play. That doesn't change. That has been his strength throughout his career, and the one thing with David that you have to be aware of is his delivery of the ball.

"It is fantastic and that is a threat. There are lots of threats that Milan have, of course, but we are well aware of that posed by David. If he plays, that will be the threat against us."

If he plays. While Old Trafford prepares to afford a hero's welcome to one of its most illustrious sons, Ferguson remains unconvinced that Beckham, who was mobbed by fans on his arrival at Manchester Airport yesterday, will start the game.

Although Milan coach Leonardo has briefed Italian reporters to expect Beckham to be in his starting 11, Ferguson is suspicious of Milan's decision to name the Brazilian forward Pato in their squad, despite doubts over his fitness, and the United manager admits the uncertainty is clouding his plans for this evening's game.

He said: "It is difficult to say what effect David will have on the tie because we don't know for certain whether he is going to start. He has not started a game since the first leg against us. I find it difficult to pick their team.

"It all depends on Pato's fitness, but he has travelled. I don't know if Beckham will start. I haven't got him down in my conclusions."

Rooney, whose two goals in the first leg secured United's cushion for the return fixture, has been declared fit to start after initially being a doubt with the inflamed knee tendons that forced him to miss Saturday's Premier League victory at Wolves.

With Ronaldo now turning out in Madrid white, Rooney has emerged as United's destructive force in the Champions League and Ferguson, who confirmed that defender Wes Brown will be sidelined for four to six weeks with a broken metatarsal, expects the 24 year-old forward to continue in the same vein.

He said: "It was a worry that Wayne's injury prevented him playing on Saturday. You looked at him on Friday and I didn't think he had any chance of playing against Milan. But he has progressed and he plays and, on his form at the moment, he would be a threat to anyone.

"That is what he will realise for us tonight – a real threat up front. I don't think that Ronaldo's departure has had anything to do with Wayne's form. I don't think that one bit. The credit must go to Wayne and his rise in the game. I just wish I had the two of them there!"

Plans by United supporters to protest against the club's owners, the Glazer family, by boycotting the first 10 minutes of the game have been abandoned.

"Our fans are not like that," Ferguson said. ''It is far too important a game for that. I'm sure that, whether they are wearing the traditional red and white or the protest green and gold scarves, they will be united and speaking with one voice to get us safely through the round."

Ferguson need not worry. The focus will be on 'Golden balls' rather than green and gold.

Beckham said: "It will be good to see Sir Alex again. He's a scary man, but in a really good way. I wanted to stay at United for my whole career, but sometimes things aren't meant to be. I've been to three great clubs since I left United, but it would have been great to stay like Ryan Giggs has."