George Russell will substitute in for Lewis Hamilton for this weekend's Sakhir Grand Prix.
The 22-year-old is yet to score a point in 36 starts, but his Williams machinery has been the worst on the grid for the last two years. He has out-qualified his team-mate in every race though, seeing off Robert Kubica last season and Nicolas Latifi this year too.
Russell's pedigree has seen him win the GP3 (2017) and F2 (2018) support series championships at the first attempt, and has been a part of the Mercedes fold for several years - testing for the team on a regular basis. However, he is yet to drive this season's car which has dominated in the hands of Hamilton and team-mate Valtteri Bottas.
"It will not be a straightforward task for George to make the transition from the Williams," admitted Mercedes team principal Toto Wolff. "But he is race-ready, and has a detailed understanding of the 2020 tyres and how they perform.
"George has shown impressive form this year with Williams, playing an instrumental role in their climb up the grid and I am optimistic that he will deliver a strong performance alongside Valtteri.
"Of course our thoughts are also with Lewis and we will be supporting him as much as we can to make a rapid recovery during this period of self-isolation."
Russell to Mercedes is one of three driver changes for this weekend's race, as Jack Aitken replaces Russell at Williams, while Pietro Fittipaldi - grandson of two-time world champion Emerson Fittipaldi - will stand-in at Haas for injured Romain Grosjean.