Drogba has scored nine goals in 15 games for Chelsea this season

The 29-year-old went under the knife on Saturday to cure the long-standing problem, and it was expected that it would keep him out until the new year.

However, Grant said: "The operation went well. It looks like it will be three weeks or something like this."

It means the Ivory Coast international should be fit to take part in the African Nations Cup in January.

News conference: Chelsea boss Avram Grant

However, he will miss Tuesday's game against Valencia in the Champions League, in which Chelsea have already qualified for the knockout stages, and also the crunch Premier League match against Arsenal on 16 December.

Drogba has scored nine goals in 15 appearances for Chelsea this season, despite the fact he "has not been 100% in the last few games" according to Grant.

Andriy Shevchenko and Claudio Pizarro must now deputise, and the Blues boss admitted Drogba's absence would be a blow, saying: "I have confidence in these players but I would feel more confident if he (Drogba) would come back.

606: DEBATE Give your reaction to news of Drogba's surgery

"You know his quality. I don't need to say it again. He is a very important striker for us. I would prefer him to be fit and play.

"But he is not here. That is a fact. We cannot fight it but we want him back as soon as possible."

Drogba underwent the operation after breaking down last Friday.

Club doctor Bryan English said at the time: "Didier's knee locked on Friday afternoon and the decision was taken to have the operation immediately in the medical interests of the player.