Ancelotti is boosted by the return of England left-back Ashley Cole for the clash at White Hart Lane as Chelsea continue their quest for League and FA Cup triumphs.
Cole broke his ankle against Everton on February 10 but has recovered sufficiently to be included in the squad. However, Ancelotti confirmed the former Arsenal defender will start among the substitutes.
Chelsea are four points clear of Manchester United, who face rivals City at Eastlands, and the Blues have already sealed an FA Cup final against Portsmouth on May 15.
But even with the spotlight firmly on Chelsea's double dreams, Ancelotti does not want his players losing focus.
"It's very easy to keep the players focused," said Ancelotti. "I don't have to work on their focus and motivation any more.
"My work is very easy, because they know what they need to do. We never speak about the double. That's not the right way to prepare at all.
"It is not a formality we will win the title. We have to play very important and difficult games and we have to pay attention.
"We have to fight again, above all tomorrow. I was very impressed with Tottenham's performance against Arsenal on Wednesday and we have to pay attention.
"They played very well. They will be the same tomorrow. It's a derby again and they are involved in the race for fourth place, so we have to pay attention.
"We have prepared very well for this game. We are focused and concentrated. We want to maintain the same gap from Manchester United. But we have to be ready. It will be a tough game tomorrow.
"Now, the title is not so sure for us. We have to fight again. We are working to win both the league and the FA Cup. We are involved in both and in a very good position, but nothing is decided.
"I've been working in football for 30 years and it's never sure until you have won. For now, we've not won."
Chelsea's hopes will be boosted by the return of Cole for the run-in.
The 29-year-old had been primed for a return against Stoke on April 25 but he has returned to full fitness even quicker than planned.
"Ashley Cole is in the squad tomorrow," said Ancelotti. "He's ready, he's fit. He'll start on the bench. I'm not surprised how quickly he's come back.
"The medical staff have worked very well on him, and he has worked hard. It's good for us to have him fit, and it's good for England as well."
German midfielder Michael Ballack believes Chelsea's fighting spirit helped them shake off the disappointment of going out of the Champions League to Inter Milan.
The Blues are now on the brink of becoming only the seventh club in history to do the double of league and FA Cup, and Ballack, 33, revealed how the players rallied after their exit to the Italians.
"We showed our spirit over the last season, otherwise we wouldn't be in this situation," said Ballack.
"To go out of the Champions League against a good opponent can always happen, and of course we have big expectations at this club, we showed in the last years we are a team that can reach the final.
"Going out early was a big disappointment and we sat together, spoke, rebuilt ourselves and bundled our strengths together again.
"It is important you don't drop your head and if you beat a team like Man United away it gives a lot of confidence - apart from Inter we have beaten all the big teams this year. We showed again we are still good enough and that's important for the mind.
"Of course it is a long season and it is important we have the mental strength, we are on top of the league and have a big target, a big chance to win two titles and that keeps us fresh in mind as well."