Kepa not at Courtois' level yet - Sarri looking to manage Chelsea expectations
Kepa completed a world-record £71.6million switch from Athletic Bilbao on Thursday as a replacement for Courtois, who joined Real Madrid.
The 23-year-old penned a seven-year deal at Stamford Bridge and is regarded as one of the most promising goalkeepers in world football.
However, Sarri has looked to lower the expectations on his new signing by insisting Kepa - who could make his debut against Huddersfield Town on Saturday - still has a lot of improving to do before he can reach the level of Courtois.
"Not at the moment," he said when asked if he can be as good as Chelsea's former keeper.
"Not at the moment for sure, but he is very young, 23 I think.
Sarri: 'He is very young, 23. I hope he can improve very fast but for the moment he is not Courtois, of course. Kovacic is very technical and [can] play between the lines of the opponent. For us, that could be very important.' #HUDCHE
— Chelsea FC (@ChelseaFC) August 10, 2018
"So I hope he can improve very fast. But for the moment he is not Courtois, of course.
"We lost one of the most important goalkeepers in the world but we bought a good, young keeper, I think one of the most important among young goalkeepers in Europe, so I'm really happy."
Mateo Kovacic has arrived at Stamford Bridge on loan from Madrid and Sarri believes the Croatia international can provide his side with something different.
"I think he has the characteristics for us," he said. "Kovacic is a very technical player.
"He is able to play between the lines of the opponent, for us that could be very important."