Williams driver George Russell will replace Lewis Hamilton at Mercedes for this weekend's Sakhir Grand Prix after Hamilton tested positive for COVID-19 on Monday.
Williams, which is an engine customer of Mercedes, agreed to release the 22-year-old for this weekend's race and has announced it will replace Russell with its reserve driver Jack Aitken.
Russell has a contract with Williams until the end of 2021, but is managed by Mercedes and has a separate long-term deal with the world champions.
When news broke of Hamilton's positive test on Monday, Mercedes approached Williams over Russell's availability and once a deal was struck the two teams confirmed the driver switch on Wednesday morning.