Gonzalo Higuain is under pressure to save his Chelsea career.
The Argentine has scored just three times since joining from Juventus on a short-team deal in January.
Once the loan concludes, Chelsea have the option to purchase Higuain for £31.3 million.
Goal reports the west London club are beginning to doubt whether they will take up the permanent option.
Maurizio Sarri was desperate to sign the 31-year-old after their successful season together at Napoli.
However, the Italian's uncertain future could also factor into the Higuain decision.