The first ever Moto3 grand prix session ended with Maverick Vinales on top the timesheets, after Thursday evening's first practice for the season-opening Qatar night race at Losail.
Avintia FTR-Honda rider Vinales, a four-time rookie 125cc race winner in 2011, moved ahead of long-time session leader Luis Salom (Kalex KTM) on his penultimate lap. Vinales then improved further on his 13th and final circulation to set a best time of 2min 9.762sec.
Salom likewise saved his best for last to trim the margin back down to 0.539sec, but that wasn't enough to prevent Luis Rossi (FTR-Honda) snatching a last-gasp second place, just 0.218sec from Vinales.
The only other rider within one-second of Vinales, the fastest rider at the final pre-season test, was Miguel Oliveira (Honda), with the leading factory KTM of Sandro Cortese 1.1sec from the top in fifth.
Cortese's team-mate Danny Kent, who like Cortese and Vinales had led one of the three official pre-season tests, only completed seven slow laps on his way to 28th place.
Second Moto3 practice will take place later this evening, after the single MotoGP Thursday session, by which time track conditions should have further improved.
Moto3, which features 250cc four-stroke machinery, has replaced the 125cc two-stroke class which ran from 1949-2011. The machinery change is instantly clear, with the deep four-stroke rumble replacing the two-stroke 'zing'.
Last year's 125cc pole time was a 2min 6.605sec, which the leading Moto3 will aim to at least threaten as the track conditions improve.
As in Moto2, Dunlop is the exclusive tyre supplier. Unlike in Moto2, open engine competition is allowed.