Maurizio Sarri bemoaned Chelsea's lack of a cutting edge as the Blues were held to a frustrating goalless draw against Everton at Stamford Bridge on Sunday.

The 59-year-old Italian extended his unbeaten start to Premier League management to a record 12 games, but was left wondering how his side fell short of a ninth win in a fractious encounter.

"We have some difficulties to approach the match from a mental point of view, maybe. I don't know," Sarri said.

"I didn't like very much the first 25 minutes. We started the match moving the ball very slow.

"It was impossible for us to be dangerous. It was very easy for the opponents to defend."

Sarri believes Chelsea have endured similar difficulties in the games with Crystal Palace, BATE Borisov and now Everton, who have not won at Stamford Bridge in 24 years.

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Everton goalkeeper Jordan Pickford denied Marcos Alonso, Alvaro Morata and Eden Hazard as Chelsea had to settle for a draw.

"In the last three matches we created few goal opportunities in relation to how much we played," Sarri added.

"In this moment maybe it's a little problem. Three matches is a very short time. Maybe it's by chance. (But) we have to be careful.

"In the second half we played at another speed, at another intensity.

"We were a bit unlucky. I am not happy, but I think we are in the right way."

Frank Clark was unbeaten in 11 Premier League games with Nottingham Forest from August to October 1994, a record Sarri has now surpassed.

"I'm really very proud about it," said the Italian, thanking the club, his players and staff.

"(But) I prefer three points today than the record."

Additional reporting by the Press Association.