Chelsea boss Graham Potter says N'Golo Kante must prove his fitness before being offered a new deal.
Kante has decided to undergo hamstring surgery this week, which will see him miss the World Cup with France.
The midfielder's deal expires in June and Potter said, "The most important thing for me and the club is that we help him to come back. That is our focus.
"He has a long road ahead of him, so we have to make sure that he gets the right treatment.
"We have to help him come back strong, and when he is back on the field, we can think about that sort of thing."
Kante isn't expected to be back for four months.