Sir Alex Ferguson says he is unsure which combination of strikers he will use against Celtic at Old Trafford tomorrow.

With Wayne Rooney in form, Dimitar Berbatov improving and Carlos Tevez desperate to show he is worth the £30million Ferguson wants to pay to make his signing permanent, the Scot has a selection dilemma.

"My torment," he said. "It is very difficult trying to gauge whether I can play the three of them together. I have been thinking about it for a couple of weeks now. It is possible, with one of them playing in behind. It is a very difficult situation because they are all terrific players."

Ferguson says his side is stronger than the team that played Celtic in the group stage two years ago. "The squad is much better," he said. "We have bought Berbatov, Tevez, Anderson and Nani since then.

"Plus, there is a general improvement in the team, which you can see in the progress we have made over the last two years. It is not easy to win leagues down here but we have done it well."

Ferguson, a former Rangers player, admits he is relishing the chance to take on the Scottish champions, where has been given a hostile reception in the past.

"These games are special," he said. "Quite apart from trying to get tickets, they give you a challenge. I have friends who would not let me forget easily if we didn't win. The press up there wouldn't. It is great.

"I am sure to get my usual great reception at Celtic. Maybe I will stand in the centre-circle this time to get the full applause."

"It is England against Scotland. The teams have the same mentality. Celtic will have a go at us. It is in their nature and history. They will be driven on by a fantastic support and we have to cope with it."