Pascal Wehrlein will pilot the Mercedes W07 during the second day of the post-Spanish Grand Prix test, replacing Esteban Ocon.
Wehrlein completed 86 laps yesterday for Manor with a best time of 1:24.297 which saw him end the day in fifth position, while Ocon completed 105 laps for Renault.
The switch was made so that Mercedes could continue testing upgrades for the rest of the season, and wanted a more experienced driver to evaluate and provide feedback.
Ocon will now have to wait until the test following the British Grand Prix in Silverstone to get his first run in the Mercedes.
The last minute change of drivers means that Lewis Hamilton will miss out on the Silverstone test, as teams must run drivers with less than three races under their belt.
As Rosberg tested yesterday and with Wehrlein behind the wheel, Mercedes has used up their two days allocation for an experienced driver in the test.
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