Fabio Quartararo was fastest by a dominant margin in first British Grand Prix practice at Silverstone, while fellow Yamaha rider Maverick Vinales crashed and Jorge Lorenzo returned to MotoGP action.
Following the cancellation of last year's British GP, Silverstone underwent a complete resurfacing ahead of the 2019 event.
Marc Marquez set pace on the new asphalt in the early stages.
The Honda rider established an early benchmark of 2m03.666s, which he soon improved to a 2m01.360s to go four tenths of a second clear of the field.
Marquez continued to lower the benchmark, moving seven tenths away from the rest with an effort of 2m01.037s after 15 minutes.
That time would be steadily chipped away at by Quartararo and Vinales, with the latter getting to within 0.126s midway through before he suffered a fast crash at Stowe corner.
He was unscathed and returned to the action in the latter stages to end up third fastest, albeit 0.740s behind Quartararo.
Marquez once again eked out a margin of four tenths with a 2m00.645s moments after Vinales's crash, but was finally usurped by Quartararo - who came close to the outright lap record with a 1m59.952s with three minutes remaining.
The Petronas SRT rider came under no threat through to the chequered flag, with Marquez only marginally improving to end the session 0.586s adrift.
Suzuki's Alex Rins leaped up to fourth after a steady start to the session, edging the second SRT bike of Franco Morbidelli and 2017 Silverstone race winner Andrea Dovizioso (Ducati).
Dovizioso was shadowed by the second works Yamaha of Valentino Rossi in seventh, with home hero Cal Crutchlow's LCR Honda heading Ducati duo Danilo Petrucci and Jack Miller (Pramac) in eighth spot.
Tito Rabat, who suffered a horrific leg injury at Silverstone during a wet fourth practice last year, was just 0.054s outside the top 10 in 11th, leading Aprilia duo Aleix Espargaro - who ran second early on - and Andrea Iannone.
In his first appearance since announcing his shock departure from KTM at the end of the season, Johann Zarco was fastest of its runners in 15th ahead of Tech3's Miguel Oliveira, who suffered a technical issue at the start of the session.
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Honda's Jorge Lorenzo brought up the rear of the field in 22nd on his first MotoGP outing since breaking his back in a crash during first practice at Assen. He ended the session 4.4s down having completed 16 laps.
Karel Abraham was the only other faller in the session, the Avintia rider also crashing at Stowe.
Practice one times
|1||Fabio Quartararo||Petronas Yamaha||1m59.952s||-||17|
|5||Franco Morbidelli||Petronas Yamaha||2m01.002s||1.050s||18|
|8||Cal Crutchlow||LCR Honda||2m01.395s||1.443s||16|
|10||Jack Miller||Pramac Ducati||2m01.535s||1.583s||15|
|11||Tito Rabat||Avintia Ducati||2m01.589s||1.637s||19|
|14||Francesco Bagnaia||Pramac Ducati||2m01.852s||1.900s||16|
|16||Miguel Oliveira||Tech3 KTM||2m01.865s||1.913s||13|
|18||Takaaki Nakagami||LCR Honda||2m02.062s||2.110s||17|
|19||Karel Abraham||Avintia Ducati||2m02.192s||2.240s||12|
|21||Hafizh Syahrin||Tech3 KTM||2m03.058s||3.106s||14|
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