Chelsea reportedly fear that title-winning manager Antonio Conte could depart the club as he has put talks over a new deal on hold.
The 47-year-old took little time to adapt to his first taste of club football outside of his Italian homeland, winning the Premier League last time out with a record number of wins.
Conte, who also guided the Blues to the FA Cup final in 2016-17, is said to have grown upset in West London after missing out on a number of his summer transfer targets.
Tiemoue Bakayoko joined from AS Monaco in a £40m deal on Saturday, while Antonio Rudiger is the other big-name arrival from Roma, but Romelu Lukaku and Leonardo Bonucci have gone elsewhere.
According to The Sun there is now further unrest behind the scenes, with a breakthrough yet to be reached regarding the four-year contract put on the table by Chelsea.
Conte, linked with Inter Milan prior to the appointment of Luciano Spalletti earlier this summer, is thought to have been offered £9.6m a year to stay at Stamford Bridge until 2021.