Chelsea's flat performance at Manchester United on Sunday could be down to a virus which struck some key players prior.
Wing-back Marcos Alonso withdrew from the Old Trafford clash with illness as Antonio Conte's Blues were beaten 2-0 by Jose Mourinho's United.
And it has since been revealed that Diego Costa and Victor Moses were also affected by the same virus but played despite feeling poorly.
The trio fell sick after a team meal on Thursday and failed to train on Friday.
It is also believed that centre-back Gary Cahill has been hit by the bug but is expected to recover in time for Saturday's FA Cup semi-final against Tottenham Hotspur at Wembley.
Despite their struggles late last week and over the weekend, Alonso, Costa and Moses are also expected to be available the weekend.