Valtteri Bottas has succeeded retired world champion Nico Rosberg as Lewis Hamilton’s team-mate at Mercedes.
The move, expected since December, also sees Brazilian Felipe Massa come out of retirement to replace the 27-year-old Finn at Williams.
Bottas has signed a one-year deal with the option for more, while Rosberg moves into an ambassadorial role.
Mercedes’ young driver Pascal Wehrlein, passed over in favour of Bottas, joins the Swiss Sauber team.
Rosberg’s shock retirement, announced just five days after he wrapped up his maiden world title, was a “challenging situation for the team to handle”, according to Mercedes team boss Toto Wolff.
“Sometimes in life, unexpected circumstances provide interesting opportunities,” he added. “Nico’s decision in December was a big surprise.
“But weathering the storm makes you more resilient and we see this as another opportunity for the team to grow.
“I think Valtteri fits very well in our team, as a driver he’s very fast, and he has also the heart in the right place.
“He shares our values and passion, and he’s modest and humble and he’s hard working.”
For Bottas, the move is the opportunity of a lifetime. He has been in F1 for four seasons and has shown well at Williams alongside first Pastor Maldonado and then Massa.
“It’s very exciting times for me,” said Bottas, whose best F1 results so far are two second places, at the British and German grands prix in 2014. (BBC Sport)