Carlo Ancelotti insists Chelsea must forget about their Barclays Premier League showdown with Manchester United on Sunday and concentrate on qualifying for the knockout stage of the Champions League.

Chelsea warmed up for their Group D clash with Atletico Madrid on Tuesday night with another 4-0 drubbing of Bolton. The win kept Chelsea top of the league and while England midfielder Frank Lampard admits these are heady times at Stamford Bridge, Ancelotti wants his squad to concentrate on victory over Madrid instead of looking ahead to their clash with Sir Alex Ferguson's side.

"Usually all the people think about the game against Manchester United but we have another important game during the week and we want to prepare well," said Ancelotti.

"It is very easy to prepare for Manchester United because it is a very important match, but we need to maintain concentration in the Champions League at this moment."

Chelsea have now scored 17 goals in their last four games without conceding and victory over Madrid, who they thumped 4-0 at Stamford Bridge a fortnight ago, will almost certainly put them into the last 16.

Lampard, who scored his fourth goal in as many games from the penalty spot against Bolton, agrees with Ancelotti that a singular attitude towards games is the key.

"We play Manchester United at the Bridge next Sunday and we wanted to be top, but not because we are facing the champions," said Lampard.

"You must have a singular attitude to every game. Now we have done well at Bolton, we have a Champions League game before we face United, and these are very exciting times for us.

"We are top of the league and we aim to create a gap at the top because we know that Manchester United are a good team and they will make things difficult for us if we don't do that.

"League position or form doesn't count much between the big clubs, it is all about form on the day. There's a danger Manchester United can close that gap, so we must make sure they don't."