Williams has officially confirmed Sergey Sirotkin as Lance Stroll's team-mate for 2018, completing the grid, with Robert Kubca appointed as reserve driver.
Sirotkin, following two years in Renault test/reserve roles, linked up with Williams for the post-race tyre test in Abu Dhabi, where he drove alongside Kubica, ostensibly in a shootout for 2018.
Sirotkin has been given the nod to join Stroll, in place of the retired Felipe Massa, and will be one of two rookies on the grid this season.
"To say I’m happy and proud to join such a famous team like Williams is an understatement," said Sirotkin, who finished third in GP2 in 2015 and 2016.
"It took a huge amount of work to get where I am, and I’m really happy and thankful to everyone involved. The result of our combined efforts has helped me achieve my dream, and rest assured the team can rely on me to deliver my best."
Deputy Team Principal Claire Williams added: "After an extensive driver evaluation process, I am thrilled to have our 2018 line-up finalised, and I’m excited to see what next season brings.
"We have taken our time to evaluate all the available options, and I’m confident Lance and Sergey can deliver the best results for the team.
"The Williams philosophy has always been to promote and develop young talent and Sergey fits right into that ethos.
"Lance has had a record-breaking debut season, and with a year now under his belt, he will be ready to hit the ground running in 2018. We have a talented driver line-up for 2018, that we are confident will deliver some exciting results for the team."
Sirotkin, 22, and Stroll, 19, will form the youngest and least experienced line-up on the grid this year.
