Chelsea boss Jose Mourinho says striker Diego Costa will be assessed on Saturday morning ahead of the home game against Stoke City.
The 26-year-old missed international games against Ukraine and Holland for Spain after suffering a level 1 hamstring tear on the biceps femoris of the left thigh in Chelsea's 3-2 win at Hull City.
The Portuguese also confirmed midfielder John Obi Mikel has fully recovered after undergoing minor knee surgery but is not in the squad to face Mark Hughes' side.
"Diego [Costa] trained yesterday and today with the group and he is not injured," Mourinho said on Friday.
"I don't know if I start with him or not because after a muscular injury and then just two days with the group,
"I need to analyse the situation with him and make a decision.
"His injury was the same as before, hamstring, and he dedicated himself to that with no days off for him or the medical department, working morning and afternoon.
"We did all the tests and scans to confirm the situation two days ago and at the moment the muscle is fine, but football is more than that, you need confidence, you need to believe you are free to express yourself at the maximum intensity and that is our doubt at the moment.
"Let's see in the next 24 hours.
"[John Obi] Mikel is fine and working all week with the group but he is very tired so he is not selected, but he is not injured.
"He is tired because he was injured for a month, he had surgery and he was not working with the group, so after four sessions with the group he needs time to adapt and needs time to be in condition."