Chelsea will not have the option to make Mateo Kovacic's loan deal permanent should the Blues want to keep the Croatian at the end of the season, reports say.
Real Madrid fought hard to keep Kovacic at the club, but the midfielder ultimately pushed for an exit this summer.
Kovacic is desperate to play more regularly and Chelsea confirmed Kovacic will join the club on a season-long loan once Thibaut Courtois completes his move to Real.
Goal claim Kovacic is set to return to Spain at the end of the campaign as there is no option-to-buy clause in the loan deal.
Sarri is considering handing Kovacic an immediate starting place alongside N'Golo Kante and fellow new signing Jorginho in midfield.
Chelsea begin their Premier League campaign at Huddersfield on Saturday and Sarri is hopeful at least two of his new additions will start.
Jorginho is in line to feature, while Sarri hopes incoming goalkeeper Kepa Arrizabalaga can play against Huddersfield as well.
Chelsea confirmed on Wednesday they had agreed a deal with Real for Courtois, who will be replaced by Kepa.
The club is also chasing Lyon midfielder Nabil Fekir, but the English transfer window's closure is fast approaching with 5pm on Thursday the deadline.