Vinales uses '16 chassis to top Valencia test
Maverick Vinales was quickest on the opening day of MotoGP post-season testing at Valencia with a 2016-spec Yamaha, as his team-mate Valentino Rossi suffered a big crash early on.
While 2017 champion Marc Marquez led for the majority of the day, first Johann Zarco and then Vinales demoted the Honda rider as the final hour approached.
Vinales set his benchmark time of 1m30.189s with a 2016 chassis and, while the team did not confirm the exact specification of the bike, it is believed that the Spaniard was using a development 2018 engine.
Rossi also had a competitive day in fourth, despite suffering a violent crash early in the day.
The Italian went off at Turn 10 and, while his bike suffered massive damage, he escaped the incident unhurt.
Tech3 rider Zarco finished the day as runner-up, two tenths off Vinales, having set his best time on the 2017-spec Yamaha.
Honda brought prototype 2018 chassis and engine for Marquez, Dani Pedrosa and Cal Crutchlow, and Marquez ended top rider in third - though his personal best 1m30.501s was set with his 2017 bike.
With Ducati set to wait until next year to debut the Desmosedici GP18, Dovizioso, Lorenzo and Danilo Petrucci were testing an evolution of the 2017 bike.
KTM duo Pol Espargaro and Bradley Smith were ninth and 12th respectively, sandwiching the Honda duo of Crutchlow and Pedrosa.
Tito Rabat completed his first day with Avintia Ducati in 13th, as Aprilia debutant Scott Redding was 15th.
LCR Honda's Takaaki Nakagami was the top rookie rider in 17th, 2.5s off the pace.
Reigning Moto2 champion Franco Morbidelli was just four hundredths of a second slower in 18th, as the order was completed by Takumi Takahashi, who replaced the injured Tom Luthi at Marc VDS Honda, and Avintia Ducati's Xavier Simeon.
Suzuki was forced to skip the day as both Andrea Iannone and Alex Rins, along with other team members, were diagnosed with minor viral infection.
Alvaro Bautista also failed to set a time due to a violent crash at Turn 1, caused by a suspected gearbox failure in his Aspar Ducati bike.
The Spaniard went to the hospital for checks, but he was cleared of any fractures.