Marc Marquez dominated a weather-affected MotoGP FP2 in Argentina, while championship leader Andrea Dovizioso was last.
The rain that fell at the end of the second Moto2 session had cleared for the start of FP2, with Marquez setting the pace with a 1:40.873s ahead of Aprilia's Scott Redding and KTM's Braldey Smith.
However, further improvements were halted as the rain returned six minutes in. Several riders ventured out into the conditions over the next 10 minutes, with more joining the action at mid distance.
Marquez got straight down to business when he returned to the circuit, bettering Honda teammate Dani Pedrosa's FP1 best with a 1:40.498s, which he soon improve to a 1:40.285s.
Behind, Yamaha's Maverick Vinales – who was 13th after FP1 – was able to improve to third, which put him eighth on the combined times as he sought a place inside the second qualifying session.
Vinales improved to a 1:40.510s in the closing stages to secure sixth in FP2 and the same position overall, with teammate Valentino Rossi 0.067 seconds adrift in seventh.
In the closing stages, Marquez cemented his position at the head of the pack with a 1:39.395s, with only Honda stablemate Cal Crutchlow on the LCR RC213V dipping into the 1:39s bracket with a 1:39.799s.
Avintia's Tito Rabat secured a provisional Q2 spot and was top Ducati rider in third on the FP2 times ahead of Andrea Iannone and Pedrosa – though the former Moto2 world champion was fourth on the combined times, splitting third-placed Pedrosa and Suzuki's Iannone.
Alex Rins was eighth on the sister GSX-RR having languished down in 21st at the end of FP1, with Alvaro Bautista and Aleix Espargaro completing the top 10, though the latter pair missed the Q2 cut on combined times in 11th and 12th to Johann Zarco and Jack Miller.
The afternoon session proved to be difficult for the factory Ducati duo of Jorge Lorenzo and Andrea Dovizioso, the pair 17th and 24th respectively, while fellow GP18 runner Danilo Petrucci was 13th.
With Petrucci 14th, Dovizioso 15th and Lorenzo 16th on the combined standings, rain in FP3 could see the trio facing Q1.
