Michael Ballack conceded yesterday that Chelsea are not playing to their full potential and identified complacency as a possible cause of their poor form. Luiz Felipe Scolari's team must beat CFR Cluj on December 9 in their final group A game to make sure of their place in the first knockout round of the Champions League, a remarkable reversal of fortune after reaching last year's final.

Chelsea have already missed out on two opportunities to qualify, losing 3-1 away to Roma this month before the 1-1 draw in Bordeaux on Wednesday, and they cannot afford a further slip-up against the Romanian champions. Ballack indicated yesterday that some of his team-mates may have been taking matches lightly, a claim that will infuriate Scolari.

“Maybe in the past, we were always favourites to qualify in the Champions League and maybe now we've taken it a bit too easy,” the Germany midfield player said.

“The problem is that we're not playing to our real level and that's strange. I don't know why we can't win away from home [in the Champions League] and cannot explain it. It's a weird situation for us, but we have to improve and have no choice.

“We're making it more difficult for ourselves to qualify than we would expect, but at least it's still in our hands. We may end up with second place, but qualifying is our target.

We're not thinking about going out. We're playing at home and need a victory, so we have to do it now.

“We didn't want it to go to the final game, but that is the situation now and we have to deal with it.”

Ballack admitted that Chelsea were fortunate to draw against Bordeaux, but he is confident that they can bounce back against Arsenal in the Barclays Premier League on Sunday.

“We were lucky to get a point in the end,” he said. “Arsenal have got the same problems as us, a Champions League game ahead of a big match, but I think it's very difficult for them to come back into the title race. Already, they see a big gap [ten points in the league] between them and us.

“At the moment, Arsenal look like a strange team. They have many problems, some from within their dressing-room, but this kind of opponent is very dangerous.

“They're like a boxer who has been knocked to the canvas. They want to get up and keep fighting, and that is what makes them so dangerous for other teams.”