A thigh problem has already kept the former Leicester midfielder from playing the first three Premier League matches, and the England international will miss another few weeks after picking up a calf injury in training.
Drinkwater is yet to make his debut for Chelsea after his £35 million switch from the King Power Stadium, but Chelsea boss Antonio Conte confirmed his latest spell on the sidelines.
'He has a muscular problem in his calf', the Italian manager said. 'I think it's very difficult to see him before the international break [at the start of October]'.
'He needs time to recover. It's a pity because he was starting to work and to improve his physical conditions. Now we have to move all these situations', the Chelsea boss added.
Conte was unable to give an exact date for Drinkwater's return, who still awaits his Chelsea debut: 'And in two, three weeks, four weeks, I don't know', Conte concluded.