Vinales tops first practice, Marquez crashes

Vinales was already third in the order when he turned a 2m02.483s lap with three minutes to go in a session run in cool and overcast conditions.

At the time that was more than a second clear of the field, but Yamaha's Jorge Lorenzo was also on a flying lap, and quickly narrowed that gap to Vinales' eventual margin of 0.282 seconds.

Championship leader Marc Marquez crashed at Farm corner in the first half of the session after losing the front end of his Honda, but he improved from eighth to third and then top spot on his final run, before Vinales and Lorenzo's improvements.

Marquez wound up third, 1.080s slower than Vinales, while Yamaha's Valentino Rossi jumped up to fourth from the bottom half of the top 10 with his final lap.

Andrea Dovizioso led the way before Marquez and Vinales' gains in the final 10 minutes and ended up the best Ducati rider in fifth, two spots ahead of Andrea Iannone, whose Desmosedici appeared to release a sizeable puff of engine smoke on his way back to the pits.

Pol Espargaro split them on his Tech3 Yamaha, while Dani Pedrosa in eighth and Pramac Ducati pair Scott Redding and Danilo Petrucci completed the top 10.

Czech Grand Prix winner Cal Crutchlow was 11th fastest for LCR Honda, as one second covered third to 14th in the order.

Marc VDS Honda's Jack Miller is returning to action after missing the Austrian and Czech GPs, and wound up 19th.

Preparing for his MotoGP debut standing in for injured Tech3 Yamaha rider Bradley Smith, Alex Lowes finished at the foot of the timesheets in the 21st, 3.742s off the pace set by Vinales.

The British rider fell in the closing minutes and was only pipped by Miller's team-mate Tito Rabat after that.