Chelsea boss Antonio Conte said he took responsibility for failing to motivate his side in Sunday's defeat by Manchester United.
The Blues lost 2-0 at Old Trafford and are now just four points ahead of Tottenham at the top of the table, having led by 10 points in March.
"We didn't play a good game and United deserved to win the game," said Conte.
"They showed more desire, more ambition, more motivation. In this case the fault is of the coach."
The Italian added he had not been able to "transfer the right concentration, desire, ambition to win this game".
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Spurs have put themselves into title contention with a run of seven successive league wins, while Chelsea have had two losses in their past four games.
The teams meet at Wembley on Saturday (17:15 BST) in the first of the weekend's FA Cup semi-finals.
"I have concern because we have to work together and find quickly the right ambition to win this title," said Conte.
"If someone thinks it's normal for Chelsea to win the title, we started as underdogs after 10th place last season.
"Tottenham is in good form and playing with enthusiasm. We must find the same."
|Southampton (h) - 25 April||Palace (a) - 26 April|
|Everton (a) - 30 April||Arsenal (h) - 30 April|
|Middlesbrough (h) - 8 May||West Ham (a) - 5 May|
|West Brom (a) - 12 May||Man Utd (h) - 14 May|
|Watford (h) - 15 May||Leicester (a) - 18 May|
|Sunderland (h) - 21 May||Hull (a) - 21 May|
Courtois injured playing basketball?
Chelsea's preparation to face Jose Mourinho's side was disrupted when goalkeeper Thibaut Courtois injured his ankle during the week.
The Blues also lost full-back Marcos Alonso just minutes before kick-off because of illness.
Conte was asked about reports Belgium international Courtois was injured while playing basketball at a promotional event.
"After a defeat it is not right to go into this situation," said the Italian.
"Courtois had an injury during the middle of the week and for this reason he wasn't available but I think it is right to focus on the game and not to find excuses."
Analysis - Conte downcast but calm
BBC Sport's chief football writer Phil McNulty
Antonio Conte has not had to deal with defeat often in an outstanding first season as Chelsea manager - and none carrying the significance of the loss at Manchester United.
Chelsea's lead over Tottenham has been reduced to four points after this reverse so Conte's response to a setback that has thrown the Premier League title wide open was always going to be intriguing.
Conte's reaction was to deflect all criticism away from his players and take sole responsibility himself.
Time will tell if Conte's approach was correct but it felt the right move. He was downcast but remained calm and his players will surely appreciate and respect his willingness to take sole responsibility by moving front and centre to shield them from the measured criticism that would have been deserved after this rare lapse.
If Conte was frustrated, he hid it well as he spoke of six cup finals awaiting Chelsea in the closing weeks while also underlining how far they have progressed from the struggles of last season and indeed the early weeks of this campaign.
Conte wisely felt his players have given him more than enough this season to allow him to shoulder the burden of the Old Trafford loss and perhaps put them even more in the mood to repay his faith in next Saturday's FA Cup semi-final against Tottenham at Wembley, as well as Chelsea's next Premier League game at home to Southampton the following Tuesday.
The Italian has barely put a foot wrong since setting Chelsea on course for the top of the Premier League after a home loss to Liverpool and a 3-0 beating at Arsenal in September - and he showed plenty of confidence in a squad that still remains title favourites.