Juventus sporting director Fabio Paratici flew to London on Thursday to negotiate terms with Chelsea over the Italian tactician.
The Blues are willing to let Sarri exit his contract, which runs until June 2021, but want over £5million in compensation.
Sky in Italy reported last night that both clubs finally shook hands on that fee and have, therefore, agreed a deal in principle.
The outlet have also stated, however, that Sarri will not be allowed to leave Chelsea until they have finalised plans for a replacement.
That replacement is likely to be Frank Lampard, the club’s all-time top scorer and current Derby manager.
Sky Sports News understand that no approach has been made as yet for Lampard, though.
The 40-year-old enjoyed a successful debut season in management with The Rams, guiding them to sixth in the Championship.
The season ended sorely with a 2-1 loss to Aston Villa in the play-off final, though, after which Lampard reiterated his happiness at the club.
“I’m not interested in the speculation,” he said.
“I’ll sit down with [Derby owner] Mel Morris over the next few days.
“I’ve got a two-year contract and I love working here.”
Whoever takes the Stamford Bridge hotseat will have to make do with the squad at their disposal, due to the two-window transfer ban Chelsea were dealt in February.
The club have protested their innocence, which came as a result of alleged wrongdoings regarding the transfers of young players, and have appealed to the Court of Arbitration for Sport.
The ban has not been suspended during the appeal, though, and the squad was dented with the departure of Eden Hazard to Real Madrid earlier this week.