Felipe Massa has announced he will bring an end to his Formula One career, for the second time, at the end of the 2017 season.
The veteran Brazilian - a runner-up in the 2008 drivers' championship for Ferrari - initially retired from F1 last year, but was soon convinced to return to Williams for a further season after the team lost Valtteri Bottas to Mercedes following Nico Rosberg's shock retirement.
Last month, Massa was quoted as saying he was "quite keen" to stay on for another campaign, but added: "I don't decide, the team decides."
On Saturday, he posted a video on his official Twitter account, confirming he is set to bid farewell to F1.
In a subsequent statement from Williams, Massa 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. Once more, I would like to say a big thank you to everyone who has supported me.
"I take so many great memories with me as I prepare for my final two races in Brazil and Abu Dhabi, and although they will be emotional, I am looking forward to ending on a high note and preparing for a new chapter in my career."
In his Twitter video, Massa indicated he may look to compete "in other races in other categories" after walking away from F1.
Williams deputy team principal Claire Williams added: "I would like to thank Felipe for all the work 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.
"We appreciate that it wasn't an easy decision for him to return, after having such an emotional send-off at the end of last year."
A popular figure in the paddock, Massa is coming to the end of his 15th F1 season. All of his 11 race wins came with Ferrari between 2006 and 2008 and he helped the team to their most recent constructors' title in the latter of those seasons.
Williams have tested Robert Kubica and Paul di Resta - who replaced Massa at this season's Hungarian Grand Prix - as they seek a partner for Lance Stroll in 2018, while Mercedes prodigy Pascal Wehrlein has been linked with the now vacant seat.