Maurizio Sarri is unsure why his Chelsea side are starting slowly in matches, after the Blues were held to a 0-0 draw by Everton.
Everton were hardly tested in the first half at Stamford Bridge, with Chelsea unable to muster a shot on target until Marcos Alonso forced Jordan Pickford into action with a rasping volley.
Pickford was more involved in the second half, pulling off a string of fine saves to deny Alvaro Morata – who also had a goal disallowed – and Eden Hazard, while Alonso hit the woodwork.
And Sarri, who has become the first manager to have gone unbeaten in the first 12 Premier League games, has acknowledged that Chelsea's persistently sluggish starts are a concern.
"I didn't like the first 25 minutes, we moved the ball too slow, it was too easy for them to defend," Sarri told a news conference.
"Then I think we have played a very good match in the first part of the second half, for 40 minutes. We were a bit unlucky. I think we are in the right way.
"I don't know [why Chelsea start slowly], it's difficult to answer.
"I don't think it is a physical problem, in the second half we played at another speed, intensity, so I don't think it is physical, maybe mental.
"We have some difficulties to approach from a mental point of view."
Chelsea's draw opened up the opportunity for Manchester City to move further clear of the Blues at the top, while Liverpool's victory earlier on Sunday has put them ahead of Sarri's side.
But the former Napoli boss does not believe that the two points dropped will prove vital.
"I don't think so," Sarri added.
"The average points of City and Liverpool is very high. It is very difficult to stay close to these teams.
"I think that, during a championship like the Premier League, this can happen to any team, a match like this."
Everton did well to restrict space for the hosts, with Jorginho particularly ineffective, and Marco Silva revealed that stopping Chelsea as a team, and not just focusing on Hazard, was the crucial factor in claiming a share of the spoils.
"If we came here just to stop Hazard, that would be the first mistake we'd have made," Silva said.
"We came here to stop Chelsea as a team. Hazard is, in my opinion, the best Premier League player of this season so far, but we created good organisation on the pitch.
"Jorginho is one of Chelsea's key players too. We blocked Jorginho fantastically.
"Hazard can create problems in any moment of the match. At some moments we blocked him. In others, we could not."
