Chelsea will face Manchester City on Sunday in a Community Shield clash, and the game will be a good test to measure how the team has progressed.
Pep Guardiola’s side were dominant last season and ended up champions with a record 100 points.
Speaking about the game against City, Sarri said: “First of all I’m looking forward to playing at Wembley because it’s my first time. The match will be very difficult for us.
“I want to win because it’s very important but at this moment of the season it’s very important to have a good performance. We have to improve and I hope to see from my team another step.
On the fitness of the players, Sarri said: “Of course the players are not at the top level, they are a bit tired maybe because of a lot of training, travelling and matches.
“So we are not at the top level but we have to try to have a good performance and result.”