PARIS -- Having threatened not to race in the last two Formula One races of the season because of a pay dispute, former world champion Kimi Raikkonen will now miss them anyway to undergo back surgery.
Lotus said in a brief statement Sunday that the surgery will rule Raikkonen out of next week's United States Grand Prix and the season-ending Brazilian GP at the end of this month.
"The team will make an announcement about the replacement driver in due course," Lotus said in the statement Sunday.
The 34-year-old Raikkonen has suffered with back pains in recent months and almost missed the Singapore GP in September when the problem flared up again.
Raikkonen's Lotus career is effectively over because he will drive for Ferrari next year.
One possibility for Lotus is to promote third driver Davide Valsecchi, although the 26-year-old Italian has no F1 experience, or to hand reserve driver Jerome d'Ambrosio the seat. The 27-year-old Belgian has 20 Grand Prix starts and was drafted into Romain Grosjean's car for last year's Italian GP after the Frenchman was handed a one-race ban.
At last weekend's Abu Dhabi GP, Raikkonen criticized the team for not paying his salary this season and threatened to pull out of the final two races of the season in protest.
He even had to be persuaded to race in Abu Dhabi, skipping media duties on the Thursday and then pulling out on lap one because of suspension damage after a minor collision with a Caterham car. He then got in a van and drove away, not answering any post-race questions.
The weekend before, tensions surfaced within the team. Raikkonen was upset when he was bluntly ordered by the team's trackside operations director Alan Permane not to hold up Grosjean during the Indian GP.