Mercedes has swapped engines for the final day of pre-season Formula 1 testing, following the shutdown on Lewis Hamilton's power unit on Thursday.
Hamilton stopped out on track on Thursday afternoon when his engine cut out as the result of an anomaly with the oil pressure.
That incident meant Hamilton could not return to the track later that day, and Mercedes took the decision to remove the power unit and send it back to its Brixworth engine headquarters for analysis to find out what went wrong.
As a result, Mercedes has been forced to swap engines for the final day of running, with Hamilton and Valtteri Bottas sharing driving duties.
It is understood that Mercedes has refitted the engine that originally failed in Bottas's car last week, which has been repaired and brought back into action.
Mercedes' headaches come off the back of its customer team Williams having to run three engines over the two weeks of testing as a result of problems it has suffered.
Williams driver George Russell suggested earlier this week that its problems were also linked to the oil system.
"There is something to do with an oil systems issue," he said.
"Obviously we run the same car in testing, so it's just one of those things.
"It's unfortunate we've had two issues over this test which has cost us quite a few laps.
"It just means the programme is a bit more pushed together. We just need to make the most of it now."