Felipe Massa's return to Williams has been confirmed for 2017 -- less than five months after he announced his plans to retire at last year's Italian Grand Prix.
Massa's return was made possible by the retirement of reigning champion Nico Rosberg in December, which left Mercedes with a free seat for 2017. The world champions targeted Massa's 2016 teammate Valtteri Bottas to replace Rosberg, meaning Williams looked to Massa to ensure it has a suitably experienced driver line-up for 2017.
Massa, who has signed a one-year deal, will embark on his 15th season as an F1 driver this year as he partners Canadian rookie Lance Stroll at the British team this year. The press release also confirmed Bottas' move to Mercedes before the world champions had announced it officially.
"I am very happy to have an opportunity to return to Williams," said Massa. "I always intended to race somewhere in 2017, but Williams is a team close to my heart and I have respect for everything it is trying to achieve.
"Valtteri has a great opportunity, given the turn of events over the winter, and I wish him all the best at Mercedes. In turn, when I was offered the chance to help Williams with their 2017 campaign, it felt like the right thing to do.
"I certainly have not lost any of my enthusiasm for racing and I'm extremely motivated to be coming back to drive the FW40."
Deputy team principal Claire Williams added: "I'm delighted that Felipe has agreed to come out of retirement to be a part of our 2017 campaign. With Valtteri having a unique opportunity to join the current constructors' champions, we have been working hard to ensure that an agreement could be made with Mercedes to give Valtteri this fantastic opportunity.
"Valtteri has been part of the Williams family since 2010 and in that time has proved a huge talent, securing nine podium finishes. I would like to take this opportunity to thank him on behalf of the whole team, and wish him a successful season as he joins Mercedes.
"Felipe has always been a much-loved member of the Williams family, and having the opportunity to work with him again is something we all look forward to. Felipe re-joining us provides stability, experience and talent to help lead us forward. He is a great asset for us."