Marquez had been the first riders to dip into the 1m40s at the Termas de Rio Hondo trail, and early on in the 45-minute session he enjoyed a one-second buffer during the resistance.
That has been eroded from the latter stages, but the Honda rider was able to stay a step ahead of his competitors, setting 2 times good enough to top the semester.
A 1m39.885so put him under three tenths ahead of Pramac Ducati rider Miller, in front of a 1m39.827s at the chequered flag left handed him 0.353s at the clear.
Cal Crutchlow (LCR Honda) temporarily went second-quickest in the final five minutes but had been defeated to the runner up area by Miller by just 0.035s.
Best of this Yamahas has been Petronas SRT rider Franco Morbidelli, 0.492s off the pace in fourth, while Aprilia’s Andrea Iannone along with KTM’s Johann Zarco both submitted times within six tenths of Marquez to complete the top six.
Qatar winner Andrea Dovizioso was seventh on the very best of the roles Ducatis, followed by Fabio Quartararo (Petronas), top Suzuki man Alex Rins and factory Yamaha rider Valentino Rossi, that completed the top 10 with a period exactly one minute slower than Marquez.
Maverick Vinales additionally suffered an indifferent session, albeit having said he’d use it wanting to clinic overtaking rivals instead of focussing on outright pace.
Vinales ended the session in 18th, 0.830s behind works Yamaha teammate Rossi.
Danilo Petrucci was clearly one of 2 riders to wreck at Flip 1 – one other being Suzuki’s Joan Mir – and consequently ended down in 20th, ahead of just Pramac’s Francesco Bagnaia along with Tech 3 KTM rider Hafizh Syahrin.