"Drogba has been living with this problem for three or four months but it is not a big problem," the Italian told the club's website on the eve of the top-of-the-table clash with leaders Manchester United at Old Trafford.
"Sometimes he has problems after a game but during the week he doesn't have any difficulty (in training)."
Ancelotti said Drogba may need a minor operation at the end of the Premier League season to be fully fit for the World Cup in South Africa in June.
"He will not need surgery now and if he needs to have an operation at the end of the season he will be ready in seven days because it will be a very little surgery," added the Chelsea coach.
Ancelotti rested Drogba for last Saturday's 7-1 drubbing of Aston Villa but said the striker, who has already scored 30 goals in all competitions for the west London side this season, would return at Old Trafford.
"He was a little bit tired before the last game so I didn't want to take the risk to put him on the pitch but now he is fit and he has to play," added the Italian.
Chelsea go into Saturday's showdown trailing United by one point with six matches to play.
