The Italian, who has taken Chelsea five points clear at the top of the Premier League in his first season in charge, said on Friday he was also very wary of third-placed Arsenal's own talented midfield.
"I have five midfielders in very good condition - (Michael) Ballack, Lampard, (John Obi) Mikel, (Michael) Essien, (Florent) Malouda -- and I have to put on the pitch only three players," he said after a session at the training ground near London.
"Frank is fit. He trained yesterday and today very well. He's in good condition and he's ready to play. He's a fantastic professional player because he stayed behind in Cobham many hours to improve his condition.
"His recovery in time for a derby game is important not just for his contribution on the pitch but also from a psychological point of view," Ancelotti said.
"We have an opportunity to use our height advantage on the free kick but football is not just a game of free kicks. We want to play better than Arsenal.
"Control of the midfield is fundamental. If they get control of the midfield they will make it very difficult for us."
Ancelotti said such a lead was not decisive at this stage of the season. What he expected from the game was fine football. He said he admired Arsenal's attacking spirit and quality on the ball in their 13 years under Arsene Wenger. His own side, so long criticised as pragmatic rather than attractive, aspired to the same kind of game.
"I think Arsenal play very well. They have had the same philosophy for many years. Chelsea can get better in this area. We can make progress but we have other qualities in spirit, in strength and in mentality," he said.
