Yamaha recruit Maverick Vinales led the way in first practice for MotoGP's season-opening Qatar Grand Prix.
After topping all four official MotoGP tests since leaving Suzuki at the end of the 2016 season, Vinales started the new campaign's first official weekend in style, setting the pace by more than half a second.
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Vinales moved to the top inside the first 15 minutes, turning a 1m55.668s to displace early leader Andrea Dovizioso.
That benchmark stood into the final five of the 45 minutes, with Marc Marquez having become Vinales's closest challenger, 0.178 seconds behind.
Jorge Lorenzo was the first rider to make a move in the closing stages, jumping up to second place and then replacing Vinales at the top with a 1m55.607s.
Ducati's new signing's time at the top was fleeting, though, with Vinales responding immediately.
Vinales set a 1m54.739s that was 0.868s faster than Lorenzo's time, with Marquez also improving to move back into second place.
There was more to come from Vinales, though, going even quicker on his next lap to a 1m54.316s.
While reigning world champion Marquez also found more pace on his final flying lap, Vinales finished the first session of the year 0.596s clear.
Marquez's Honda team-mate Dani Pedrosa also flew late to claim third, ahead of Tech3 Yamaha rookie Jonas Folger, while Lorenzo fell to fifth, 1.291s slower than Vinales.
Avintia Ducati's Loris Baz jumped up to sixth at the very end, leading Cal Crutchlow and Johan Zarco on the second Tech3 Yamaha.
Crutchlow's session started with an apparent engine problem on the run to Turn 1 on his first flying lap, having to park his LCR Honda after it let out a plume of oil smoke.
The Briton rejoined the session on his spare bike, after changing his oil-soaked boots.
Valentino Rossi had to settle for ninth, 1.483s slower than Yamaha team-mate Vinales, despite jumping up from 12th to sixth in the closing stages.
Aleix Espargaro was 10th for Aprilia, while rookie team-mate Sam Lowes was the first rider to crash in the new season, 13 minutes in.
Lowes lost his RS-GP at Turn 9 and missed the bulk of the running but got back out late and finished 22nd.
Karel Abraham and Jack Miller also crashed, separately at Turn 2 in the closing minutes, and were 15th and 17th fastest.
Dovizioso wound up 11th, ahead of Scott Redding and the best of the Suzukis in the hands of Andrea Iannone.
Suzuki was the only manufacturer to run the fairing it has homologated to replace the now-banned winglets, with both Iannone and Alex Rins sporting them and Rins finishing 18th.
Pol Espargaro led the KTMs in the Austrian manufacturer's first weekend as a full-time MotoGP competitor.
Espargaro turned a 1m57.630s early the session, finishing 3.314s off the pace in 21st, with team-mate Bradley Smith a further 0.484s adrift and 23rd.
Opening practice is the sole Thursday track action in the unique-to-Qatar evening timetable, with the next two sessions on Friday night before qualifying on Saturday.
PRACTICE ONE TIMES: