Mercedes has become the latest team to have trouble with its MGU-K at the start of the final pre-season test.
Following Honda's well-documented problems with an MGU-K seal during the second test, Mercedes had its running halted at lunchtime on Thursday due to an MGU-K failure. With 48 laps on the board in the morning session, Mercedes failed to add to that total as Lewis Hamilton's running was cut short.
Nico Rosberg is due to be in the car on Friday, with Hamilton again driving on Saturday. Mercedes also hit reliability issues at the start of the second test, with Hamilton withdrawing due to illness before Pascal Wehrlein's running was limited due to technical issues.
Hamilton had set an impressive time on the medium tyre early in the day, but was knocked off the top of the timing screens by Felipe Massa as the Williams became the first car to dip under the 1m24s mark at the Circuit de Catalunya courtesy of a soft tyre run.
McLaren earlier brought an end to its running on day one after just seven laps due to a hydraulic leak.
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Driver line-ups for the final test
Click here for the gallery from day one of the final test
