MILAN: AC Milan and Manchester United will go head-to-head at the San Siro in arguably the biggest tie of the Champions League round of 16 on Tuesday.

One of the main reasons for the tie's magnitude will be the return of David Beckham to Old Trafford as an away team player for the first time since he left United in 2003 to join Real Madrid. United manager Sir Alex Ferguson recently spoke of his concern that there would be a circus surrounding Beckham's return but that is looking slightly less likely now.

Beckham has been dropped for Milan's last two matches, having previously occupied the right-sided berth in the club's three-pronged attack. The signing of Mancini from Inter Milan and young forward Alexandre Pato's return from injury have seen Beckham drop to the bench as a replacement for one of the midfield trio.

But even without 'Golden Balls', this promises to be a potential classic. It will be the fifth time the two sides meet in the knockout stages of Europe's premier club competition and for the first time it is the English champions who will be heading in as favourites.

United have won three of their four home matches against Milan but have never managed to progress against the wily Italians, losing every one of their four away games. The last time the two sides met a Wayne Rooney-inspired United came from behind to win first-leg match 3-2 at Old Trafford. Brazilian Kaka produced a dazzling display in the return leg, though, as Milan romped to a 3-0 success in Italy to reach the final, where they beat Liverpool 2-1 to lift their seventh European Cup crown.

Milan even look upon United as a lucky omen as every time they have faced United, they have gone on to reach the final -- although three of their four previous meetings were in the semi-finals. Yet this Milan team is shorn of Kaka and the likes of Andrea Pirlo, Clarence Seedorf, Alessandro Nesta and Gennaro Gattuso are all the wrong side of 30. The return of Pato from injury in Friday's 3-2 win over Udinese will have been a relief to his compatriot coach Leonardo and the player himself insists he will be in optimal shape on Tuesday.

But despite his importance to Milan and his rejuvenated countryman Ronaldinho also playing for Milan, the most in-form striker on the pitch will be playing for the opposition. If there is one player who worries the Italians it is Premier League top goalscorer Wayne Rooney, but the powerful forward won't be taking Milan lightly.

Rooney has not forgotten the lesson Milan gave United three years ago, in particular from Seedorf. "For me, Seedorf is probably the best player I've ever played against. When we played Milan at the San Siro a few years ago, he was unbelievable," said the Liverpool-born player.

"Milan have a number of players who can score goals, particularly from set-pieces, so I think we'll have to be wary of that. They have Pirlo and Becks -- some great players. Ronaldinho is a special player, too. He's unbelievable when he's on form. I saw recently that he was voted Player of the Decade, so that shows how much of a talent he is. We'll need to be at our best to beat them."