Mercedes hints at progress with tyre weakness

During in-season testing on the same circuit Tuesday McLaren detected a water leak on the first lap and worked all day to fix it, completing only 17 laps and two timed runs.

Bottas completed 143 laps in total despite causing a red flag midway through the day when the auto stopped with a mechanical issue related to the steering wheel. That led to an extended period of downtime in the garage as the team conducted a series of systems checks, but the vehicle reappeared in the early afternoon.

"We don't like that, at all", team boss Toto Wolff told reporters after Bottas twice obeyed radio instructions to let the faster Hamilton through to chase eventual victor and championship leader Vettel. Having failed to start the Bahrain Grand Prix due to an MGU-H problem and following further reliability issues for Honda on Tuesday, Vandoorne was able to complete 81 laps and post a 1:32.108 late in the day, leaving him within a second of Bottas.

Having been testing tires for Pirelli on the opening day, Vettel was driving for Ferrari in a normal test session on Wednesday but managed just eight laps in the opening few hours as the team worked through some reliability issues discovered during setup changes. However, if the team can sync its mapping and brake-by-wire system with the Carbon Industrie brakes, they could be introduced as soon as the Russian Grand Prix next week. He completed a mammoth 126 laps with a best time within a second of Bottas. "You're trying to take parts off from other cars that function".

Russian 21-year-old Sergey Sirotkin was at the wheel with the Renault and completed 90 laps in his new role as the team's test driver.

Bottas struggled with rear tyre life during the race, slipping to third, and admitted afterwards that he and Mercedes had to investigate the cause.

  • Arturo Norris