Williams has confirmed Sergey Sirotkin will race for its team alongside Lance Stroll this year, filling the last available place on Formula One's 2018 grid.
The news ends months of speculation about Williams' driver line-up and was announced alongside news that Robert Kubica, who had been in the running for Sirotkin's seat, will join the team as a reserve and development driver. The pair took part in an end-of-season test with Williams last year and deputy team principal Claire Williams said the decision to opt for the 22-year-old Russian over the 33-year-old Pole had been based on the data the team had on both drivers.
"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," said deputy team principal Claire Willliams. "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."
Chief technical officer Paddy Lowe added: "We have conducted a rigorous and exhaustive driver evaluation process. Ultimately, Sergey impressed the team with his driving pace and talent, technical feedback and work ethic, both at the factory and trackside in Abu Dhabi."
Sirotkin is backed by the Russian SMP Racing programme and drove in GP2 in 2015 and 2016 as well as working with Renault as a test driver for the last two years. He is believed to be bringing around €15 million in funding to the team and has joined on a multi-year deal.
The partnership of Sirotkin and Stroll represents the least experienced driver line-up on the grid, with Stroll just one rookie season in to his multi-year agreement with the team. However, the 19-year-old Canadian says he is looking forward to working with his new teammate.
"First of all I would like to welcome Sergey to Williams and I am looking forward to having him as my teammate," Stroll said. "I know Sergey and I am sure we will very quickly form a close working relationship. I really enjoyed my rookie season with the team, and there were a number of memorable highlights, on which I'll look to build on in the coming season. I'm looking forward to Barcelona, and driving the new FW41 for the first time."
Sirotkin added: "To say I'm happy and proud to join such a famous team like Williams is an understatement. 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."