Reece James is awaiting the results from a scan on his hamstring amid concerns of another significant injury at Chelsea.
The 23-year-old could face weeks or even months out after being substituted in the 76th minute of the 1-1 draw with Liverpool on Sunday.
Mauricio Pochettino initially played down fears and explained he was “tired” and that he wanted to “avoid the risk” of playing him for longer in the opening Premier League match of the season.
Chelsea are now less positive as they wait for the latest update ahead of a trip to face West Ham at the London Stadium.
There a longer term concerns surrounding James’s fitness issues after he missed almost 50 per cent of Chelsea’s matches last season due to two successive knee injuries and a hamstring problem.
Ben Chilwell, the club’s vice-captain, is in line to step up and take the armband while Malo Gusto will deputise at right-back whenever James is missing.
Gusto, 20, is highly regarded at Stamford Bridge, arriving after six months on loan at Lyon following his £26.3million transfer in January.