Kimi Raikkonen Sunday admitted back pain nearly kept him out of the Singapore Grand Prix and could put him in doubt for the next race in South Korea after he braved the injury to place third.
The former world champion needed intense physiotherapy to race in Singapore and it came up trumps as he made it onto the podium behind Sebastian Vettel and Fernando Alonso.
Afterwards the 33-year-old Finn, who is moving to Ferrari next season, said it was "not for sure" that he'd make the next race in South Korea in two weeks' time.
"I didn't feel it too much but obviously it's not ideal. Yesterday was pretty bad, I almost didn't drive," he said.
"So I think we have to be happy with that and hope there's no problems for the next race.
"But it's not the first time and I know that I have some work to do before the end of the year so we have to see what we can do."
Asked whether he would be fit for South Korea, Raikkonen said: "Not for sure. We have to see."
Raikkonen's back pain was a flare-up of a long-standing problem that dates back to a testing crash in 2001.
But his latest comments, about a race that is still a fortnight away, are likely to deepen intrigue over his relationship with Lotus following a rocky week.
After being confirmed as Ferrari driver for next year, Raikkonen said a dispute over money prompted the move, and claimed he had not been paid by his current team.
"I like to race, obviously that's the only reason why I'm here," he said this week.
Lotus team principal Eric Boullier later fired back at Raikkonen and insisted the Finn would get all his money in due course.
The injury could also cause concern within Ferrari ahead of Raikkonen's return to the team next year.