The influential trio have yet to return for pre-season training as they recover from the World Cup, meaning new Blues manager Sarri must wait to discuss their futures.
Speaking after his first Chelsea game ended in a 1-0 friendly win over Perth Glory, the Italian coach told Sky Sports News: “It’s a pleasure to have Courtois, to have Willian, to have Hazard, but it (their futures) doesn’t depend on me, not only on me.
“So, we have to wait. I’m confident.”
Goalkeeper Courtois has only a year remaining on his contract, while forwards Hazard and Willian each have an additional 12 months.
Asked when he would have a chance to talk to the players, Sarri added: “Face to face, I think at the end of the month because they will come to Cobham (training ground) at the end of the month.”
Italian Sarri has plenty to sort out at Stamford Bridge, with the club’s failure to qualify for the Champions League not helping his cause to convince key players to stay.
Defender David Luiz, who became a peripheral figure under Antonio Conte last season, played the full 90 minutes in Perth as he attempts to get his career back on track.
He believes the club must keep hold of their best players, while backing compatriot Willian to remain in west London.
“I think that the press sell the players every single year. They buy players, they sell players,” he said.
“I hope the trio can stay because they are fantastic players, fantastic talents and we need the best players in Chelsea.
“I speak to Willian almost every day, he loves to play for Chelsea. I think he’s going to stay.”
Sarri has had little chance to impose his tactics or philosophy on his new squad after the club jetted off Down Under in the immediate aftermath of his unveiling last week.
Spanish forward Pedro scored the only goal at the Optus Stadium, netting inside five minutes.
While N’Golo Kante, Gary Cahill, and Andreas Christensen were among the other important absentees, there was a debut for £50million midfielder Jorginho.
Sarri, who replaced the sacked Conte on July 14, was satisfied with some of his side’s display but admits they have to improve “very quickly”.
According to the club’s Twitter account, Sarri and his team immediately boarded a flight back to London after the game, and the 59-year-old is keen to start working with his players at Cobham.
“The result was not the mirror of the game, but the performance is more important in this period,” the former Napoli boss told chelseafc.com.
“I am satisfied by the performance in the first half and the first 15 minutes of the second half, not the last 30 minutes.
“We have to go back to Cobham and work very hard. We know we have to improve very quickly.
“I expect us to improve match by match. It’s not easy at this moment because we are without 12 players from the World Cup.”
Sarri’s second game in charge will be a friendly against Inter Milan next Saturday.
Chelsea have been looking to sign a new keeper in anticipation of Courtois’ departure, but were stymied in their efforts to sign Brazil’s Alisson, who left Roma to join Liverpool last week. However, Kasper Schmeichel and former Chelsea goalkeeper Petr Cech have been identified as alternatives.
The Blues are seemingly resigned to losing Courtois, who is entering the final season of his contract and could walk away for free next summer.
For Madrid, the signing of the 26-year-old Belgian who won the Golden Glove award at this summer’s World Cup would signal the end of a lengthy effort to find a new keeper. Though Keylor Navas was signed in 2014 and has acquitted himself well, Los Blancos have been looking to make a big-name signing at the position for quite a while.
Moves for Manchester United‘s David de Gea and Athletic Bilbao’s Kepa Arrizabalaga proved unsuccessful, but Courtois would be a marquee signing, given his World Cup form and his relatively young age, which could see him spend a decade at his next club.
With speculation emerging this week that the current deputy to Marcelo at the position, Theo Hernandez, is considering leaving the club in search of more playing time, Telles is being lined up as a replacement.
Madrid officials were reportedly in Porto on Monday to discuss a potential transfer for the 25-year-old, who is said to have a €40million release clause in his contract.
Telles has previously been linked with Los Blancos, back in 2015. Juventus are also reportedly interested in the in-demand full-back.