Kimi Raikkonen has undergone a successful operation on his back.
Raikkonen announced on Sunday he would miss the final two grands prix of the season in the United States this weekend and Brazil next due to a long-standing back issue.
Raikkonen almost pulled out of the Singapore Grand Prix in September due to the pain he was experiencing from a trapped nerve, a throwback to a testing accident during his rookie year in 2001 with Sauber.
Deciding the time was now right for the surgery, especially given issues behind the scenes regarding non-payment of his £10million-per-year salary, Raikkonen opted to skip the the races in Austin and Sao Paolo.
A Lotus statement read: "As planned, Kimi underwent back surgery yesterday (Thursday) at The University Hospital of Strasbourg.
"Lotus is happy to report the operation was totally successful, according to Professor Afshin Gangi.
"Kimi will now rest for a few days and will start his recovery process as early as next week. Everyone at the track and at Enstone wishes him a quick recovery."
Reserve driver Davide Valsecchi, meanwhile, has launched a tirade at the team after being overlooked as replacement for Raikkonen.
Last year's GP2 champion has spent the entire year on the sidelines waiting for an opportunity, only to be ignored when a chance arose.
Lotus, after failing to lure Michael Schumacher out of retirement for a second time, or Nico Hulkenberg from Sauber, instead turned to Heikki Kovalainen, who was axed from Caterham at the end of last year.
Speaking to the Italian media, a bitter Valsecchi said: "It's a huge blow to me. From the sporting point of view it's a tragedy.
"It makes me angry to have lost the battle with Kovalainen, who is not a great champion, not even an active driver. His last results were five years ago.
"If they had taken Hulkenberg I could have understood, even (Pastor) Maldonado, but this...
"I was sure from the point of view of motivation and desire to achieve, the team would have taken me and I would have been right up there.
"Perhaps I lack experience, but what chance do you have to gain any?
"Nevertheless, things change quickly in F1, so I won't give up and I will be ready if they need me in Brazil."