Chelsea boss Jose Mourinho won't risk the fitness of Diego Costa.
The striker has scored in both of Chelsea's matches this season but has been unable to train for the past two days.
"He has to try a light training session to see if the reaction is positive," Mourinho said.
"If it's positive, we'll take him to Everton to play or be on the bench. Let's see.
"If the reaction is not positive on Friday, obviously we don't select him. At this moment, I don't know much."
