Chelsea can close to within five points of their bitter rivals with a game in hand if they beat Fulham at Craven Cottage on Sunday, and Sarri has not discounted the possibility of his team fighting their way back to a third-place finish.
Sarri stated this ahead of Chelsea's Premier League clash with Fulham on Sunday.
"The selection of Willy Caballero in goal for the Blues and the reaction he got from his players in midweek suggested to me that Maurizio Sarri is very much in charge at the Bridge and has the full backing of his squad".
But, speaking at a press conference on Friday, Sarri wouldn't be drawn on which match Kepa would start in, raising the prospect of the world's most expensive keeper potentially missing a second successive league game.
Real's Ramos handed two-game European ban
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"Kepa's the first choice, of course, he is very young, he's improving, we know very well that he can become one of the best goalkeepers in Europe", Sarri added. On a personal note this is something I started working towards seven years ago when I was a Spurs player. I have to understand, and I think I also need to have an English mentality. "I understand what is at stake and that it's a London derby against a very, very good football team", he said.
Asked about Ranieri's departure, Sarri said: "I'm really very sorry. He is very important in our group and dressing room, so we need to consider him".
"We ran for 15 kilometres on Sunday on average, and the average of the last match was 12km".
"We need to continue, first of all, with the performance because the result is only a outcome", Sarri added.