GARY CALDWELL admits there is a gulf between Champions League holders Manchester United and Celtic.

It was cruelly exposed as Sir Alex Ferguson's men demolished the Parkhead side 3-0 at Old Trafford. But Caldwell, who does not accept mental scars of this mauling will afflict them, said: "What happened last night should not affect us when we play United at Parkhead in two weeks."

The defender, who required a pain-killing injection to play in a midfield holding role, added: "Better teams than us have gone to Old Trafford and been taught a lesson.

"We can't hide away and crumble. We've got to stand and be men and come back from this."

Caldwell accepts they will have to raise their game to have any chance of grabbing the win vital to their Group E campaign and said: "We want to keep our home record going. But they are a very good side and it's going to be another tough night when United come to Glasgow."

A defeat, allied to a Villarreal victory in Aalborg, would end their bid to reach the Last 16 for the third year in a row.

Caldwell continued with admirable honesty: "We've always said getting to the Last 16 for the past two years were amazing achievements.

"We are punching above our weight at times. But we'll keep on doing that, keep on battling away and see where it takes us."

Manager Gordon Strachan has already conceded that, with just one point from their three games, Celtic are already looking at the Uefa Cup as their realistic target.

Caldwell just wants the real Celtic to show itself and said: "We're all hurting because we wanted to be in a better position.

"We've had some harsh lessons this year and played some right good sides. We have to learn from that and get better.

"Quality at this level counts, and United had it all over the park. They are the best team in Europe."

Caldwell hopes to be fit to face Hibs on Saturday.