- Those dropped points have left them in fourth place, 10 points adrift of leaders City after 15 games
- Sarri accused his Chelsea players of a collective "blackout" at the first sign of trouble against Fulham
- City, who finished 30 points better off than Chelsea last season, are the best team in Europe, Sarri said
Maurizio Sarri said he knew he would face challenges at Chelsea despite a bright start to the season as he prepares his team to face Premier League leaders Manchester City on Saturday.
Chelsea were unbeaten in their first 12 Premier League games but lost 2-1 at Wolves on Wednesday - their second defeat in their past three league games.
Those dropped points have left them in fourth place, 10 points adrift of leaders City after 15 games.
"I knew very well that sooner or later we have to face difficulties," Sarri said on Friday. "When you change the way of playing, the way of football, you need to change the mentality.
"You need to change the mentality in 25 minds, so it's not a short way. It's very difficult."
Pep Guardiola's City have won 13 of their Premier League games and are unbeaten in the league since April.
Sarri, who has experienced defeat to Guardiola with Napoli and Chelsea in August's Community Shield, was asked how his side can beat City.