Antonio Conte claims he failed to motivate his players as Chelsea lost 2-0 at Old Trafford against Manchester United.
Goals at the start of either half from Rashford and Ander Herrera condemned Mourinho’s former side to their second defeat in four games.
The Blues’ lead over second-placed Tottenham is now down to four points with six games remaining, while United boosted their own hopes of reaching the top four by extending their unbeaten league run to 22 games.
The Italian said: “I think they deserved to win. They showed more desire than us and more motivation, but in this case the fault is with the coach.
“In this case I wasn’t able to transfer the right motivation to play this type of game.”
Chelsea have a favourable run-in but Conte is wary having dropped points in recent weeks, including a costly slip-up at home to Crystal Palace at the beginning of April.
He added: “I am concerned, we have to work together and find quickly the right desire and ambition to win this title.
“For us it is a fantastic target. For me if we were able to reach this target it would be a miracle. We must understand this and find the right motivation.
“We stay in a great position, but Tottenham are in good form and playing very well and with enthusiasm. We must have the same.”