Maurizio Sarri wants to see more aggression from his Chelsea players from the start of matches.
Third-placed Chelsea are unbeaten in their opening 12 games under the Italian and face Tottenham at Wembley on Saturday.
Sarri used his pre-match media conference on Friday to again play down his side’s title chances and promote Manchester City’s.
He also reiterated his optimism that Eden Hazard will extend his contract, after midfielder N’Golo Kante committed his future to Stamford Bridge until 2023.
Sarri stated his unhappiness with a “mental problem” at the start of the last three games, which he wishes to resolve.
“We had problems with the approach to the match, but not only that, because we have some problem also in the beginning of the second half,” he said.
“We have to be careful. We have to be focused on this problem. The problem was that the opponents were more aggressive, more determined than us.
“It’s not a tactical problem, it’s not a physical problem. We have to approach the match in a different way, for application and determination.”
The opponents may help provide an answer for Sarri, given Tottenham in a derby is different to Crystal Palace, BATE Borisov and Everton, whose physicality appeared to unnerve Chelsea.
Sarri has been impressed with “very dangerous” Spurs.
“We have to be careful not to lose the ball in our half. They are very dangerous in those situations,” he said.