Maverick Vinales held onto top stop in FP2 at the Argentina MotoGP, while world champion Marc Marquez improved greatly from the morning session to claim second.
Marquez, who finished down in 11th in FP1, initially set a fastest time of 1m40.670s in the afternoon session using a medium front and a hard rear tyre.
Aspar rider Alvaro Bautista briefly took over at the top, but Marquez hit the front again after switching to hard tyres front and rear.
It looked like that might remain as the quickest time, but with the session winding down and the threat of rain looming for FP3 on Saturday, most of the riders opted to run soft rear tyres for a time attack in the closing stages to avoid a potential Q1 appearance.
Several riders were able to beat Marquez's time – including the Spaniard himself – but once again it was wonderkid Maverick Vinales who had the measure of them all, posting a 1m39.477s with the same tyre combination to beat Marquez by a 0.301 seconds.
— Maverick Viñales (@maverickmack25) April 7, 2017
Karel Abraham and Alvaro Bautista took third and fourth respectively for Aspar Ducati, followed by Danilo Petrucci for Pramac Ducati.
Loriz Baz narrowly pipped Cal Crutchlow for Avintia Ducati.
While Marquez was able to improve dramatically from FP1, the same could not be said for several other big names, who may have to tackle Q1 on Saturday if forecast rain affects third practice.
Dani Pedrosa was 13th on his Honda after suffering a low-speed crash at Turn 13 during his second run, followed by Andrea Dovizioso in the first of the Ducatis.
Valentino Rossi had to settle for 16th, 1.054s off the pace of Yamaha team-mate Vinales, while Jorge Lorenzo was a further two places further back.