Felipe Massa has topped the timesheets on the first day of the final F1 pre-season test at the Circuit de Catalunya, while Mercedes joined McLaren in being forced to curtail its day early.

Brazilian Massa utilised the soft tyres during the afternoon session to leap to the top of the timesheets with a 1min 23.500secs lap, an effort that arguably offers the first hint of Williams' true pace with three days of testing to go.

Faster than Romain Grosjean's best lap from the first F1 test around the Spanish circuit, Massa was more than seven tenths faster than Marcus Ericsson, who scaled the timesheets during a final hour as he focused on performance runs in the Sauber C34.

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Prior to that, the Swede had been working on race simulations, completing more than 120 laps before the chequered flag was dropped, to end the day as the busiest driver on track.

Behind Ericsson, Hamilton was third fastest on a day that had started well as he quickly got his best lap time down to a 1min 24.881secs on the medium compound tyres in the Mercedes, a benchmark that would hold firm at the top heading into lunch time.

However, the W06 wouldn't re-emerge in the afternoon as Mercedes worked to fix an issue on the Hybrid system, which was later diagnosed as an MGU-K failure. Eventually, Mercedes would call an end to the day early, leaving Hamilton to complete just 48 laps in total for the first proper set-back of the winter for the title-defending team.

Daniil Kvyat brought out a red flag early in the day but went on to fourth fastest in the Red Bull, ahead of Grosjean in the Lotus, Kimi Raikkonen in the Ferrari and Carlos Sainz in the Toro Rosso, the latter losing much of the afternoon after stopping the revised STR10 on track with a technical issue.

Finally, Jenson Button brought up the rear for McLaren as yet more technical issues - this time a hydraulic leak that necessitates a full Honda power unit change - consigned him to a paltry seven laps. Kevin Magnussen is currently scheduled to drive the problematic car tomorrow.