Honda rider Marc Marquez dominated a rain-disrupted third MotoGP free practice session at the Circuit of the Americas in Austin.
Marquez was among the few riders to better his Friday laptime before weather intervened, and ended up four tenths clear of nearest rival Johann Zarco, who likewise posted his personal best lap of the weekend.
The Frenchman had looked set to miss out on an automatic Q2 spot after placing just 13th overall in the first two practice sessions, but forced his way into the top 10 with a strong showing.
Zarco's FP3 gains left Dani Pedrosa on the cusp of Q1, but the Honda rider, competing at COTA despite the recent surgery on his left wrist, found extra pace to secure a Q2 berth at the expense of Aprilia's Aleix Espargaro.
The threat of rain spurred on early track activity in the 45-minute session, and it was Marquez who quickly usurped the top spot, ending his first run half a second clear in the FP3 leaderboards - and just a tenth off Andrea Iannone's Friday benchmark.
This was followed by a marginally quicker effort from the reigning champion as the session ticked over the halfway point, Marquez logging a 2m04.608s and coming up just 0.009s short of Suzuki rider Iannone's laptime.
The traditional late-FP3 qualifying-sim shoot-out that was expected to follow was then scuppered by the arrival of rain with 10 minutes left on the clock, which froze the running order.
Iannone, whose Friday lap remains the weekend's benchmark, ended FP3 third, with LCR Honda's Cal Crutchlow fourth and Ducati's Andrea Dovizioso fifth.
The latter was another rider to post an improved laptime in the Saturday morning practice session, and did so while running Ducati's aero package on his GP18.
Pedrosa placed sixth in the session, with Yamaha teammates Maverick Vinales and Valentino Rossi in seventh and ninth, split by Suzuki's Alex Rins – with all of them making it through to Q2.
Scott Redding made up the top 10 in FP3 despite taking a tumble early on at the Turn 14 right-hander.
Ducati's Jorge Lorenzo was 11th in FP3, but advanced to Q2 on the strength of his Friday laptime.