Didier Drogba passed fit for United showdown
Drogba was rested for last weekend's thumping 7-1 win over Aston Villa and has since missed two days of training while nursing a knee problem.
But Drogba has now shrugged off the injury, sustained in a training ground accident with Yuri Zhirkov, and will be fit to start the game against United at Old Trafford.
"Drogba was out but trained very good today," Ancelotti said on Thursday. "We have trained very well this week. The team is fit. He is a very important player. He has scored 30 goals. The other strikers did a great job against Villa without him, but he is very important to us."
The Ivory Coast international has scored 24 goals in 26 Premier League games this season, second only to the absent Rooney, who will be missing due to minor ankle ligament damage.
However Drogba's record against United is very poor as the Chelsea striker has scored only once in 13 games in all competitions against Sir Alex Ferguson's side.
United are currently one point clear of Chelsea in first place in the Premier League.