Maurizio Sarri admitted he is worried about his Chelsea team’s “mentality” after they fell to a 2-0 defeat at Everton that severely damages their hopes of a top-four finish in the Premier League.

Richarlison and Gylfi Sigurdsson, converting his own saved penalty, scored the second-half goals at Goodison Park on Sunday that halted Chelsea’s recent league improvements and marked Everton’s first win over ‘Big Six’ opposition in 26 games, a run dating back to January 2017.

But the goals followed a first half of utter Chelsea domination in which they somehow failed to beat Everton’s England goalkeeper Jordan Pickford and the subsequent collapse has clearly concerned the London club’s manager.

“I’m worried about our mentality,” said Sarri. “I think the situation is clear. We played probably the best 45 minutes of the season then, suddenly, at the beginning of the second half, we stopped playing. I don’t know why.”

The Italian added: “We played really very well until the last minute of the first half and then suddenly very badly in the first minute of the second half.

“It’s very difficult for players to explain to me the change. Very difficult for me to explain to you the change, probably it is a mental block I think.”

Richarlison struck in the 49th minute, after Sigurdsson’s right-wing corner had been met by a powerful header from Dominic Calvert-Lewin which Kepa Arrizabalaga saved well on his goal-line.

But Everton’s Brazilian forward reacted first to force the rebound over the line from close range, a goal that came largely against the run of play.

Arrizabalaga had saved a good effort from Andre Gomes seconds earlier and did likewise in keeping out Sigurdsson’s 71st-minute penalty, awarded after Marcos Alonso stood on the foot of Richarlison.

‘Big limit’

But the Iceland international kept his composure from the rebound, completing the routine task of tapping the ball into the open goal, denying Chelsea the chance to go level on points with Arsenal, who are one point behind third-placed arch-rivals Tottenham Hotspur.

“At the moment, it is our limit,” added Sarri. “I think because if we are able to play like in the first half, with consistency, I think we are in another position in the table but we have this problem.

“It is a big limit for is because we lost a similar match in Wolverhampton, today we lost so for us at the moment it’s a big limit.

“Today was really, really important for us so now we have one less opportunity but I think we have to fight to defend those opportunities.”

The best of Chelsea’s first-half chances saw Eden Hazard strike the post from a curling sixth minute shot, with Gonzalo Higuain missing a glorious opening moments later, under pressure from Yerry Mina.

Pickford also made a superb second-half save, from Callum Hudson-Odoi’s fierce shot although, by then, the outcome had been settled with Everton fans enjoying a bonus moment when former star Ross Barkley, who left the Liverpool club in controversial fashion, was substituted by Sarri to a chorus of boos.

“To be honest, I didn’t know those numbers before the match,” said Everton manager Marco Silva of his side’s long winless run against leading clubs in the Premier League.

“It’s not a normal thing for a club like us, not winning so many times against strong sides.

“But for our quality as a club how big we are as a club, it’s something that can’t happen again. It’s up to us to work together for it to be more normal for us to beat these strong sides.”