Ancelotti warned his players not to take Spurs lightly in their must-win game, despite their appalling record at Stamford Bridge and their recent run of one victory in 10 games.
The last two months have seen Harry Redknapp's men fall four points behind Manchester City in the race for the country's final Champions League spot with just five matches remaining.
Three of those are away at Chelsea - where they have never won in the Premier League era - Liverpool and City, meaning they could be struggle even to secure a Europa League spot if their poor form continues.
But Ancelotti insisted: "They are involved in the fight for fourth place.
"They will try to do everything against us because now they have a gap to close to Man City."
Source: PA
Source: PA