Chelsea manager Jose Mourinho is yet to decide whether to risk striker Diego Costa for the Barclays Premier League leaders' clash with Stoke this evening.
Costa suffered a recurrence of his hamstring problem in last month's 3-2 win at Hull and withdrew from international duty with Spain.
Chelsea's top scorer will be in the squad for the Stamford Bridge fixture, but may not start.
Mourinho said: "Diego trained (on Thursday and Friday) with the group. He's not injured. I don't know if I start with him or not.
Asked the long-term solution to Costa's recurring problems, Mourinho insisted an operation would be undertaken only if there was no alternative.
Chelsea have only one game a week for the season run-in, apart from when they meet Leicester in midweek later this month in a match rearranged due to the Capital One Cup final.
"It's better," Mourinho said. "With a normal week of work, playing one match every weekend, normally he should be fine."
Chelsea are six points clear of second-placed Manchester City with that game in hand, but Mourinho believes the title race is open and even fourth-placed Manchester United, who are eight points behind, are in contention.
"With eight matches to go it is a difficult gap from the first to fifth, but the points difference between second, third and fourth make me feel that they are there," Mourinho added.
"In the last matches they (United) become consistent in results and also the quality of their performances.
"We need six victories and one draw in nine matches, so a good situation for us, a situation that all the other clubs would like, but it's pure mathematics."