Mark Wilson will face the greatest challenge of his career tonight should he be chosen to shackle Cristiano Ronaldo. The Celtic defender has played the last couple of games at left-back and is enjoying a rare sustained run in the team.

Mark Wilson will face the greatest challenge of his career tonight should he be chosen to shackle Cristiano Ronaldo.

The Celtic defender has played the last couple of games at left-back and is enjoying a rare sustained run in the team, but he will need all his experience to nullify the threat of the current Fifpro World Player of the Year.

"I've played against Ronaldinho in the past, but I think Ronaldo just now is incredible," said Wilson. "He is probably as good an opponent as any of our players have ever come up against. He is a guy who can do everything. He looks unhappy when he scores just now, but he is still scoring loads.

"It's not a great sign for us. Lee Naylor did a great job against him a couple of years ago when Celtic beat United 1-0 at Parkhead. I was on the bench that night and Lee kept him quiet for the whole game. We will be looking to do that again. You're looking for a midfielder to help you out. It's difficult. Any defender in the world coming up against him faces a tough task. So if you have someone there helping you, you can maybe stand off him and push him in the park. If you tackle him early, maybe that is your best chance."

Wilson occupied the right-back berth against United at Old Trafford a fortnight ago and saw the Champions League holders at close quarters. He believes Dimitar Berbatov will pose another huge problem for Celtic tonight. The Bulgarian has been in excellent form in recent weeks and scored twice against Celtic at Old Trafford.

"Berbatov came to Man United and a few people were saying he was slow to start, but he has kicked on now," Wilson added. "He looks almost like he is not trying, and you get that feeling when you are playing against him, too, but he can just spark into life.

"Wayne Rooney and Ronaldo take all the limelight, but he is capable of causing us massive problems. Individually and as a team they are by far the best to have come to Celtic Park in a long time."

Wilson believes Celtic must defend as a team and try to keep their shape in order to cope with United's quick, attacking football. He contrasted their style with that of Barcelona, who beat Celtic 3-2 at Parkhead in the last 16 earlier this year.

"United just go for it," he said. "Barcelona, like many European teams, like to slow the game down and pass the ball. It gives you a chance to get players behind the ball, but if you lose the ball against Man United when you're attacking, they have so much pace that they can kill you.

"It's difficult to not get stretched against them because of their pace and the fact that they like to stay out wide. Split-second decisions on the night will decide how the game is going to go and if we don't get dragged over the pitch, then we will have a chance."

Celtic were their own worst enemies in Manchester a fortnight ago. As well as being pinned back by the home side for long spells, they failed to retain enough possession when they did have the ball. Wilson insists that they must improve that aspect of their game if they are to get a result tonight.

"The manager said after the Old Trafford game that we didn't pass the ball anywhere near as well as we can, so it is going to be very important this time. United will have a lot of possession, that is inevitable, but it is important when we get it that we don't just rush up the pitch and give them the ball straight back. It's important the boys keep their heads when they do have the ball and don't let the crowd influence them too much in terms of rushing passes."