Lewis Hamilton has lauded Valtteri Bottas as his greatest Formula 1 team-mate and says he "will be missed" after it was confirmed that the Finnish driver would be leaving Mercedes at the end of the 2021 season.
Bottas has now signed for Alfa Romeo for 2022, with Monday's announcement paving the way for George Russell to join Mercedes - which will be confirmed this week.
The deal is a sign that Mercedes are looking to the future, but also brings to an end what has been a harmonious and successful partnership between Hamilton and Bottas. While Bottas has only won nine races since joining in 2017 and hasn't beaten Hamilton over a season, the pair have helped Mercedes to a record streak of constructors' titles.
Hamilton paid tribute to Bottas, his fifth F1 team-mate, on social media.
"I'm immensely proud to have worked alongside Valtteri Bottas for the last five years," posted Hamilton. "Together, we've been part of a team that has delivered four Constructors' Championships, and we've motivated one another to keep pushing through the ups and the downs.
"He has been the best team-mate I've had the pleasure of working with. Your speed and resilience has been impressive but where you truly stand out to me is the human being you are.
"You are greater than you know and I know there's a bright future ahead for you.
"Thank you Valtteri for all of your support and amazing contributions to this team. You will be missed. I wish you all the best for your future endeavours. Let's finish off strong and get that 8th for the team."
Hamilton's four previous team-mates were Fernando Alonso, Heikki Kovalainen, Jenson Button and Nico Rosberg. Rosberg was Bottas' only predecessor next to Hamilton at Mercedes, and the pair had an infamously hostile rivalry, which ended in 2016 after the German's retirement post-title win.
Bottas has signed a multi-year deal with Alfa Romeo, the Ferrari-backed Swiss team who are currently ninth in the 2021 standings.
Mercedes: 'Not easy decision' to replace Bottas
Mercedes will finally confirm Russell as Hamilton's team-mate this week, with an announcement potentially on Tuesday. It follows a summer of deliberation from F1's world champions as they weighed the known quantity of Bottas - who has pushed but not beaten Hamilton - versus the rising British star.
In the end, they opted for the driver they have supported and seen shone at Williams for the last three years, but insisted it was a tough call and that Bottas "absolutely deserved to stay".
"This hasn't been an easy process or a straightforward decision for us," said Mercedes boss Toto Wolff. "Valtteri has done a fantastic job over the past five seasons and he has made an essential contribution to our success and to our growth.
"Together with Lewis, he has built a benchmark partnership between two team-mates in the sport, and that has been a valuable weapon in our championship battles and pushed us to achieve unprecedented success.
"He would absolutely have deserved to stay with the team, and I am pleased that he has been able to choose an exciting challenge with Alfa next year to continue his career at the top level of the sport; when the time comes, he will leave us with huge goodwill from every single member of the team, and he will forever be part of the Mercedes family."
Mercedes are currently 12 points ahead of Red Bull in their bid for a record-extending eighth Constructors' Championship.