Walter Smith pinning hopes on a 'rusty' Wayne Rooney

• Rooney in training with his teammates in Manchester today. Picture: Getty

But Smith knows his side could find themselves up against a revitalised Rooney instead in what is a vital game for the Scottish champions.

The 25-year-old is set to start in Glasgow after making his comeback from injury as a substitute against Wigan at the weekend, having completed a period of rehabilitation in the United States for an ankle problem. He has also been forced to overcome personal problems but Smith is bracing himself for Rooney to be back to his best.

He said: "Once you get rid of all the stuff that was going on in the background, they will be looking forward to getting him back playing again.

"I can only hope tomorrow that he's a little bit rusty through lack of activity in terms of games.

"From a Manchester United point of view, they will be delighted to have him back."

As far as Smith is concerned, Rooney is not the only player to be wary of when the Group C leaders come calling, insisting United as a team will pose a collective threat.

He added: "Manchester United are one of the most experienced Champions League teams, they know how to handle the situation, and they have shown that already in this season's Champions League.

"I listened to commentators on their game the other week and they were saying they are not playing so well and yet they don't lose any games.

"It's a remarkable thing to be able to, not play well and not lose.

"They are still up there in the Premiership. The standards at the club are extremely high and we will have to match that tomorrow night."

Madjid Bougherra and Maurice Edu are both sidelined for the clash, while Sasa Papac is rated doubtful, meaning Smith will have to rethink the ultra-defensive formation which has served him well in the majority of European outings so far.