There was one question Alex Ferguson could not answer after Manchester United’s rollercoaster 3-2 victory over AC Milan.

Whether it will be good enough I dont know,” he mused ahead of next week’s second leg in what will be a hostile San Siro stadium. “We will be going over there, and its a big game now, with a big chance.”

The suspicion has to be that United have indeed done enough.

Yes, Milan are likely to pull United’s threadbare defence apart again — as Kaka did so convincingly in scoring twice at Old Trafford — even if Rio Ferdinand recovers from a groin strain in time.

And, yes, Milan have the kind of European experience that twentysomethings Wayne Rooney and Cristiano Ronaldo are still dreaming of. Milan have reached two Champions League finals in the last four years, winning in 2003 and losing to Liverpool in 2005, and feature the likes of four-times winner Paolo Maldini and three-times winner Clarence Seedorf in their ranks. Coach Carlo Ancelotti even won the European Cup twice as a player.

But goal-happy United pose the greater attacking threat and a never-say-die spirit embodied in Rooney’s stoppage-time winner on Tuesday. A goal down at kickoff next week, Milan know they have to get forward — thereby exposing themselves to Ronaldo’s pace and Rooney’s finishing on the break.

Ryan Giggs summed up the challenge as United bid to repeat their 1999 Champions League success. “We’ve got to go out there with confidence and the second half here in mind - knowing that if we keep the tempo up and keep our shape we’ve a great chance of creating chances,” he said.

Maldini was not so sure. “They have their weapons and we have ours,” he said. “Kaka is a great player and he shows it in the big games.”

But will Kaka be enough?

Trevor Huggins is Reuters sports correspondent based in London