Kimi Raikkonen will miss the last two races of the Formula One season in Texas and Brazil after deciding to have back surgery next week, the Lotus driver's manager said on Sunday.
Steve Robertson told Finnish newspaper Turun Sanomat and the autosport.com website that the 2007 world champion, who is moving to Ferrari next season, could no longer put off the operation.
"In an ideal world it would have been nice to finish the season with Lotus," he said. "However, due to the severe pain that Kimi is having, sadly it is not possible."
Raikkonen has a long-standing back problem, which flared up in Singapore in September.
However he also complained before this month's Abu Dhabi Grand Prix that he had not been paid by Lotus, who have financial problems, and told reporters he had considered not attending that race.
A Lotus spokesman could not immediately confirm the reports.