George Russell will leave Williams at the end of the 2021 season, after getting the call up from Mercedes to become teammate to Lewis Hamilton on a new, long-term deal.
Russell made his F1 debut with Williams in 2019 and has been present for the team's transition from being owned by the Williams family to the new structure under Dorilton Capital. He has also led their resurgence from being the slowest team on the grid to becoming midfield runners capable of points finishes once again.
Russell admitted part of him is sad to be leaving behind the family that he's grown up with at Williams.
"It's a special day for me personally and professionally, but also a day of mixed emotions," he said.
"I'm excited and humbled to be joining Mercedes next year, which is a huge career step, but it also means I'll be saying goodbye to my teammates and friends at Williams.
"It has been an honour working alongside every member of the team, and an honour to represent the Williams name in F1.
"Since I joined in 2019, we have worked tirelessly to push each other forward and bring the team back up the grid where it belongs. We've battled for every qualifying position, every point, and every tenth of a second.
"No matter how tough it's been, nobody has ever given up, and that has inspired me every day.
"I've loved every moment in what I'd describe as a true heart and soul racing team, and I'll be pushing harder than ever to make sure we end our story in the best possible way."
Williams' Jost Capito, CEO and Team Principal, said the team are proud to see their young driver step up to what should be the very front of the Formula 1 pecking order in 2022, knowing that the skills he's honed came with their help.
"Over the past three years, it's been clear to every member of staff here at Williams just how dedicated, focused, and talented George is through his contributions to the team both on and off track," Capito told media, including RacingNews365.com, in the wake of Mercedes' announcement.
"He has all the characteristics necessary to achieve the greatest success in our sport and we are therefore delighted for him, both as a team and me personally, to see him rewarded with the opportunity to test himself at Mercedes.
"We will watch his progress with interest and pride, knowing the role Williams has played in developing his considerable skills. We were of course aware of this possibility coming to fruition and therefore have a number of strong driver options available to us.
"We now look forward to shaping our future line-up that will help us take the next step in our exciting journey as a team and will make any announcement in due course."
With Russell now ticking off the races until he departs for Mercedes, he has vowed not to get distracted from the task of helping Williams consolidate their position in the Constructors' Championship.
"For now, though, I have nine more races as a Williams driver, and I want to make sure they are the best nine of my time with the team," he said.
"Then, and only then, can I turn my attention to 2022."