Marc Marquez narrowly beat Repsol Honda teammate Dani Pedrosa to set the pace in the second MotoGP practice session of the weekend in Argentina, as Honda got four bikes inside the top five.
With track conditions improving from the earlier session, topped by Andrea Dovizioso, the riders wasted little time in beating the FP1 benchmark set by the Italian, Pedrosa doing so first with a 1m43.158s.
That was immediately bettered by Marquez, who took the top spot with a 1m42.622s, before the two-time champion improved to a 1m42.523s and then to a 1m42.196s.
With 20 minutes to go, Marquez then became the first man to dip beneath the 1m42s with a 1m41.898s, before setting the final benchmark for the session, a 1m41.579s, with just a minute remaining.
Pedrosa made a late improvement just moments before the chequered flag to set a time just 0.025s down on his teammate, giving the works Repsol Honda team a one-two.
The duo were half a second ahead of Suzuki's Maverick Vinales, who recovered from a crash at Turn 3 midway through the session to set the third best time.
Honda satellite riders Jack Miller (Marc VDS) and Cal Crutchlow (LCR) turned in impressive laps to complete the top five, Pramac rider Scott Redding the top Ducati representative in sixth.
It was another quiet session for Yamaha as Valentino Rossi could do no better than seventh, just under a second off the pace, and Jorge Lorenzo was left to languish in P14 after running wide on his last hot lap.
With rain forecast for Saturday, the reigning champion runs the risk of having to fight his way through the first phase of qualifying, finishing the day two tenths outside the top 10.
Aleix Espargaro (Suzuki) crashed twice during the session on his way to the eighth fastest time, ahead of Bradley Smith on the best of the Tech 3 Yamahas and FP1 pacesetter Dovizioso.
Pol Espargaro suffered his second crash of the weekend at Turn 1 late in the session, finishing P13, while Yonny Hernandez fell off his Aspar Ducati early on trying to overtake the Tech 3 rider around the outside of Turn 13.
As in the earlier session, Pramac Ducati's Michele Pirro did not set a time as he is travelling to Argentina from a two-day test at Valencia - and will be in action on Saturday.