Chelsea have been rocked by an apparent hamstring injury suffered by Diego Costa.
He could now face an extended period on the sidelines after reportedly pulling up with a hamstring strain on Wednesday.
The severity of the knock is as yet undetermined but there are fears such an injury could keep him out for as many as six weeks.
Despite concerns Stamford Bridge medical staff are yet to officially rule the 25-year-old out of the trip to Everton this weekend, according to the Guardian.
