Felipe Massa has announced his retirement from Formula One at the end of the 2017 season.
The Williams driver intended to quit F1 at the end of 2016 but completed a retirement U-turn to return to Williams after Valtteri Bottas moved to Mercedes following the retirement of world champion Nico Rosberg.
In a statement, the Brazilian said: "As everyone knows, after announcing my retirement from Formula One last year, I agreed to return this season to help Williams when the call came.
"I have now enjoyed four great years with the team, but my career in Formula One will finally come to an end this season."
Claire Williams, Deputy Team Principal, Williams Martini Racing added: "I would like to thank Felipe for all he has done for the team over the last four years. It has been an absolute pleasure to work with him.
"We are especially grateful that he agreed to postpone his retirement from Formula One for a year, after Valtteri joined Mercedes, which demonstrated the depth of the relationship we built during our time together."
Massa's decision, announced in a social media post one week before his home race at the Brazilian Grand Prix, opens up a vacant seat at Williams for 2018, with the Grove-based team already evaluating which driver should be placed alongside Canadian rookie Lance Stroll.
Robert Kubica, Paul di Resta, Pascal Wehrlein and Daniil Kvyat are all understood to be in the running to take Massa's seat, with Williams expected to make an announcement after the season-ending Abu Dhabi Grand Prix.
Thanks for the support love you guys 😉 pic.twitter.com/TUCcXIYHVv
— Felipe Massa (@MassaFelipe19) November 4, 2017
Massa's career dates back to his debut with Sauber in 2002 and consists of 11 victories and 41 podiums to date. He came closest to winning the title in 2008 but missed out on the championship by a single point to Lewis Hamilton.
The dramatic finale took place at his home race in Sao Paulo and saw him cross the line as champion, only for Hamilton to make up a crucial position in the final corner of the final lap to take the points he needed to pip Massa to the title.
His victory at the 2008 Brazilian Grand Prix was his final race win the sport. He recovered from an horrific accident at the 2009 Hungarian Grand Prix to return to the Ferrari cockpit in 2010, before departing the Scuderia at the end of 2013.
Massa subsequently signed for Williams, scoring a shock pole position at the 2014 Austrian Grand Prix, as well as claiming five podiums during his four year spell at the team. His retirement at the end of the year should bring to an end a career spanning 269 starts between 2002 and 2017.