Mercedes reserve driver Pascal Wehrlein topped the timesheets on a rain-delayed opening day of the post-Austrian Grand Prix test at the Red Bull Ring.
The morning session saw just a lap apiece from McLaren's Stoffel Vandoorne and Ferrari's Antonio Fuoco as heavy rain hit the circuit, prompting an early red flag. The delay meant the session was pushed back to 8pm local time.
After lunch the rain had eased off and the circuit went back to green flags, with the only interruption after that point a brief red flag for Fuoco after crashing at Turn 1. Mercedes reserve Wehrlein - who was due to drive for Force India until the morning of the session - picked up where the team left off at the weekend by topping the session with a 1:11.005, which was his best lap in 67 laps.
Wehrlein's replacement at Force India, Esteban Ocon, finished two tenths behind in the Mercedes-powered Force India, which was trialling several new parts ahead of the debut of its B-spec VJM08 in Silverstone. Max Verstappen finished third in the Toro Rosso after completing 73 laps, ahead of the Ferrari of Fuoco, whose session ended after the shunt midway through the afternoon.
Romain Grosjean's 1:11.509 put Lotus fifth in the standings after a day devoted to aero tests, putting the team ahead of Red Bull junior Pierre Gasly, who completed 78 laps for the Renault-powered team. Sauber's Raffaele Marciello did not emerge until late into the afternoon but was able to complete 53 laps due to the extended running time.
GP2 championship leader Stoffel Vandoorne managed 76 laps in the MP4-30 and finished the day in eighth. McLaren was forced to change its testing plan due to the extent of damage suffered by Fernando Alonso, who returns to the cockpit on Wednesday, on the first lap of the Austrian Grand Prix - the Spaniard had been running new parts, including a new nose, which were badly damaged after contact with Kimi Raikkonen's Ferrari. The team has some spare new parts which it will run with Alonso on Wednesday.
Susie Wolff rounded off the time sheet for Williams, finishing over two seconds behind Wehrlein's benchmark - though headline times are largely irrelevant during testing days. Williams was trialling a unique rear winglet during the test and was hoping to build on the success of Felipe Massa's podium at Sunday's grand prix.
Like it did at the post-Spanish Grand Prix tests in Barcelona, Manor has decided to miss the two days of testing due to the cost implications.
Though the early rain prompted discussions about extending testing to Thursday, the test will stick to its original two-day schedule. Fernando Alonso, Daniel Ricciardo, Nico Rosberg, Valtteri Bottas and Felipe Nasr return for their respective teams, while Esteban Gutierrez gets a chance at Ferrari, Jolyon Palmer takes over at Lotus, Wehrlein switches back to Force India and DTM champion Marco Wittmann makes his F1 debut with Toro Rosso.