Drogba was forced to serve a three-match ban following his foul-mouthed confrontation with Norwegian referee Tom Henning Ovrebo at the end of Chelsea's Champions League semi-final defeat by Barcelona in May.

The in-form striker, who has scored nine goals in the Premier League already this season, has now served his punishment and could return in tomorrow's Group D clash against Atletico - where Chelsea have the chance of sealing a spot in the last 16.

Ancelotti was asked whether he has spoken to the 31-year-old forward about the incident in a bid to make sure there would be no repeat this season.

The Italian, who did not take charge of Chelsea until this summer and was therefore not in the hot-seat when Drogba made his outburst after the Barcelona match at Stamford Bridge, said he had not and preferred to have his striker focus on tomorrow's game.

"I didn't know what happened (last season). I saw what happened. I didn't speak with him about this, I'd rather speak about the results of the last three games," said Ancelotti, whose side have recorded wins of 5-0, 4-0 and 4-0 since defeating Atletico 4-0 at Stamford Bridge a fortnight ago.

"I told him to prepare for his return tomorrow. Tomorrow he will return to work for the team - and he is ready to work."

Although Drogba has been in prolific form in the league, Chelsea have barely missed him in Europe, winning all three of their matches in Group D whilst scoring six goals and conceding none.

That success has left Chelsea three points clear of second-placed Porto at the midway point of the group stages, and knowing that a victory tomorrow would secure them a berth in the knockout stages.

Chelsea will fancy their chances of achieving that against an Atletico side who have suffered a dismal start to the season both domestically and in Europe.

The Spanish outfit have won just once in nine Primera Division games and find themselves in the relegation zone, while the Rojiblancos are bottom of Group D in the Champions League with just a single point.

Despite that poor form though, Ancelotti is wary about the threat posed by their opponents tomorrow, who last week replaced the sacked Abel Resino with former Valencia and Benfica coach Quique Sanchez Flores.

The Chelsea coach continued: "Quique Sanchez Flores is a good coach, he had a good experience at Valencia and I think he can do a good job at Atletico Madrid.

"We have respect for Atletico because they have very good players; (Tomas) Ujfalusi is a good defender, (Sergio) Aguero is a very good striker, (Diego) Forlan is a very good striker, Maxi is a very good midfielder.

"I think now is not a very good moment for them, but I think they have the quality to get out of their situation," added Ancelotti.

Chelsea were closely linked with Atletico striker Aguero this summer, but while Ancelotti spoke of his admiration for the 21-year-old, he insisted the Argentinian was not on their radar at present.

Chelsea have been banned by FIFA from registering any new players during the next two transfer windows, although the Premier League leaders have appealed to the Court of Arbitration for Sport (CAS) against the ruling. "For his age he (Aguero) is one of the most important and best-quality players in the world," said Ancelotti.

"Aguero is very young, he is a fantastic striker and has a lot of quality. Every big club are looking at this player, but we are not thinking of buying anyone again at this moment.