Bottas fastest on second day of in-season test

Power chases result for IndyCar momentum

His lap tally was in stark contrast to Ferrari, as Vettel endured frustrations with a large amount of time lost in the pits.

The Finnish driver lapped the desert track an astonishing 143 times on a mammoth day of running for Mercedes, clocking a best time of 1m 31.280s in cooler conditions towards the end of the session.

"We need to improve the vehicle and our knowledge about the tyres so that we are in a better position in the next race". That led to an extended period of downtime in the garage as the team conducted a series of systems checks, but the auto reappeared in the early afternoon.

Carlos Sainz was third during an afternoon of running for Toro Rosso, but it was Stoffel Vandoorne in fourth place who is likely to be the happiest of all 12 drivers to run on Wednesday.

McLaren have produced a promising chassis this season but have been unable to show its potential because of Honda s failure to deliver a reliable engine.

McLaren's racing director Eric Boullier dubbed Tuesday the team's best test day of 2017 after Vandoorne was able to push some of the car's settings without a repeat of the MGU-H issues the team has faced since arriving in Bahrain. The team has struggled with its brakes since it entered F1 past year and despite a successful update from Brembo at the Chinese Grand Prix, a switch Carbon Industrie could still be on the cards. Perez propped up the timesheets in P12, 3.7 seconds off Bottas' fastest time. The team is waiting on a major update ahead of the European season, meaning it was mainly focusing on tyre and setup options with Perez clearly focusing on long runs in the afternoon.

Gary Paffett returned to an official Formula One test for the first time since 2013 and racked up 59 laps in the Williams during the morning. "You're trying to take parts off from other cars that function".

Ferrari's challenge is slightly different from Mercedes, in that Vettel's team is on top of its race performance but has proved lacking on single-lap pace.