Mercedes Team Principal Toto Wolff insists it was not a "straightforward" decision to drop Valtteri Bottas for the 2022 Formula 1 season.
Bottas will join Alfa Romeo in 2022 on a multi-year deal, paving the way for George Russell to partner Lewis Hamilton at the Silver Arrows. It ends a four-year relationship between Bottas and Mercedes, which began in 2017.
"This hasn't been an easy process or a straightforward decision for us," said 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 teammates in the sport, and that has been a valuable weapon in our championship battles and pushed us to achieve unprecedented success."
Bottas has won nine Grands Prix with Mercedes, helping them continue their dominance in F1's turbo-hybrid era.
Wolff says Bottas "would absolutely have deserved to stay" with Mercedes, but is pleased to see him continue in F1 with Alfa Romeo.
"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," continued Wolff.
"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."