Kimi Raikkonen will not compete in the final two races of the season, leaving Lotus with a considerable handicap in their fight for second place in the constructors' championship.
Raikkonen has decided skip the races at the United Stated and Brazil to order to undergo surgery.
Finnish newspaper Turun Sanomat reports that the former World Champion will get treated for his backpain. The Finn has been suffering with intermittent back issues since a crash at Magny-Cours in 2001 where he was conducting private testing for Sauber.
"The experts have recommended surgery, and he will undergo the treatment next Thursday in Salzburg", confirmed Steve Robertson, the manager of Räikkonen.
"It is evidently disappointing to conclude the relationship with Lotus this way after two successful seasons. Meanwhile Kimi cannot afford to wait any longer. It is essential to resolve the back issues for good in order to be able to start the 2014 season in the best possible conditions".
The departure was undoubtedly helped by Lotus not having paid their Finnish driver for his driving in 2013, even though the team gave guarantees that payment will be completed at the end of the year.