"He is the best player at the club and we need Chelsea to keep the best players", Fabregas told a news conference ahead of the club's first preseason game against Perth Glory on Monday.
Both Hazard and Courtois have been linked with summer moves to Spanish giants Real Madrid, with the latter entering the final year of his contract with the west London club. Fekir also made 6 substitute appearances in France's World Cup-winning campaign. Subscribe to our SMS sports service by texting "SPORTS" to 22840.
Former Napoli boss Sarri was appointed on a three-year contract on Saturday, just 24 hours after the sacking of compatriot Conte. A professional and ethical attitude is very important, more than apologies.
"This is what any manager wants to do, this is what any club wants to do".
"I won't lie, I speak to him often", said Fabregas.
Hazard, though, is on holiday and Sarri admitted phoning him would not be sufficient.
"I'd like to meet them face to face".
How realistic is it that Chelsea will lose two huge stars this summer?
After Courtois returned to Chelsea from a outstanding loan spell with Atletico Madrid, Cech found himself demoted to second-choice goalkeeper at Stamford Bridge and left for Arsenal at the start of the 2015/16 in a £10 million deal.
Sarri continued: "For me this is a hard challenge, but a fascinating one".
"I think our task as managers is growing the players that we have". It is hard, but I have not asked anyone anything.
"I have not asked anything of anyone".
The 59-year-old Sarri, who was coach of Serie A club Napoli from 2015-18, is delighted to be at Chelsea.
"This is a post-World Cup time", said Sarri.
Manchester United and Barcelona are interested in the Brazilian, who had a frosty relationship with Antonio Conte.
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