The 27-year-old has already been ruled out of the Europa League group match at home to Belarus outfit BATE Borisov on Thursday when Chelsea will hope to make it three wins from three games.
Hazard put his back injury down to being kicked so much in last Saturday’s 2-2 Premier League draw with Manchester United and the Belgian, the Premier League’s top scorer with seven goals, is now in a race to be fit for Sunday.
“Tomorrow he (Hazard) is out for sure,” said Sarri on Wednesday.
“He has a back problem. We are trying to solve the problem for Sunday.”
Sarri expects to rotate his starting line-up to face BATE, but fears a bigger problem for Sunday’s Burnley trip.
“This match is not a big problem, because we have to play after five days, from the last match,” said Sarri.
“The problem will be on Sunday, because on Sunday we will play after 65 hours. So we need to change some of them.
“For example Jorginho we need to rest now, because he played 90 minutes the two matches with the international team (Italy), and then he played for 100 minutes in the last match. It’s time to rest him.
“(Andreas) Christensen I think will be on the pitch, Loftus (Ruben Loftus-Cheek) maybe.”
For more news your way, download The Citizen’s app for iOS and Android.
Download our app and read this and other great stories on the move. Available for Android and iOS.