Tony Arbolino took his maiden Moto3 pole ahead of Marco Bezzecchi in a weather-affected Argentina qualifying.
Despite there still being damp patches on track, the field had switched to slicks for the first time on Saturday after initial exploratory laps on wets.
Arbolino set the early pace on his Marinelli Snipers Honda with a 1:58.672s, though this was quickly bettered by home rider Gabriel Rodrigo with a 1:58.131s.
Arbolino returned to top spot soon after with a 1:55.969s, but was once again deposed by Rodrigo by two tenths, before Marco Bezzecchi stormed clear with a 1:54.088s.
The Prustel GP rider's time stood until the final 15 minutes, when Arbolino returned to the top of the pile with a 1:54.020s, improving on his next lap to a 1:53.782s.
Just moments later, rain appeared in the first sector and remained through to the chequered flag, securing Arbolino a debut pole in grand prix racing.
Three tenths adrift was Bezzecchi, who will start on the front row for the first time in his career, with Rodrigo third for his home race.
Adam Norrodin heads the second row for his best every qualifying result having missed out on the top three by just 0.016s, with Enea Bastianini and FP3 pacesetter Fabio Di Giannantonio shoving Niccolo Antonelli back to the third row.
Aron Canet pipped Qatar race winner Jorge Martin – who lost several minutes of track time at the start of the session after his Gresini team forgot to fit his bike's bellypan – to eighth by just 0.008s in the closing stages, while Andrea Migno recovered from a crash at Turn 1 to complete the top 10 for the Nieto team.
Top rookie Juame Masia edged the injured Albert Arenas to 11th, while Ayumu Sasaki headed Dennis Foggia and Lorenzo Dalla Porta to round out the top 15.
