Barcelona F1 test: Valtteri Bottas leads final morning for Williams

Like his team-mate Felipe Massa a day earlier, Bottas completed a qualifying simulation on super-soft tyres before lunch, recording a time of 1m23.063s.

The lap was two-tenths faster than Massa's effort but still 0.041 seconds slower than Mercedes' Lewis Hamilton went on softs on Saturday afternoon.

McLaren endured another disastrous session with the Australian Grand Prix looming large.

An hour into the day, the team confirmed it was undertaking "system checks", and a sensor problem eventually required the removal of the Honda engine before Jenson Button could emerge five minutes before the break.

There was trouble for Red Bull, too, with Daniel Ricciardo turning only 10 laps due to an ERS problem that caused the Australian to stop at the end of pitlane and prompted the morning's only red flag.

The top four drivers all set their times on the super-softs, with Sebastian Vettel, Felipe Nasr and Sergio Perez doing so in the hour before lunch.

Nasr was the busiest driver of the morning, completing 73 laps in his Sauber, while Perez turned 54 to continue Force India's reliable run since rolling out its new car on Friday morning.

Nico Rosberg ended the morning an unfamiliar fifth, having focused on medium and hard compound programmes, including longer runs.

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