Outside the top ten for much of the session, Zarco made his final time attack count as he pipped Miller and MotoGP champion Fabio Quartararo.
Despite track conditions heating up for FP2, lap times were immediately on pace with Alex Rins’ best effort from FP1.
Although a lot of the circuit’s bumps were smoothed out, turn nine, a big problem area in 2021 nearly caught out Jorge Martin as the Pramac rider lost the front not once, but twice.
Thankfully, the Spaniard held on and managed to stay upright.
While Martin was wrestling his Desmosedici GP22 around turn nine, Miller had no such issues aboard his factory machine as he went five tenths clear of anyone.
The Australian set a time of 2:03.567s before Bastianini and Aleix Espargaro joined him in going underneath the best FP1 time.
After two disastrous Grand Prix, Andrea Dovizioso began to show good pace during the early stages of FP2. The Italian went as high as P8 before quick laps from Francesco Bagnaia, Marc Marquez and Joan Mir bumped the three-time runner-up down to 11th.
As was the case in FP1, both Aprilia riders started to find their rhythm as Espargaro went P3, before Maverick Vnales put his RS-GP22 into second.
A MotoGP winner for the first time last weekend, Espargaro has so far looked like a contender for the podium, while Vinales has shown even more potential.
Rins the strongest?
However, as the field began to close up, Rins and his new soft rear tyre moved the benchmark time a whole five tenths further away.
Rins then backed up his time of 2:03.030s with another lap within a tenth of a second.
Although it was very good pace from the Suzuki rider, the ease with which he was achieving it should be alarming for the rest of the grid heading into qualifying.
With five of the six manufacturers represented inside the top ten with a quarter of FP2 to go, the only ones missing were KTM who were surprisingly struggling.
Not coming as easy for Mir…
With his team-mate fastest, Mir was pushing hard in order to match Rins’s efforts but the 2020 world champion appeared to be struggling.
However, his next lap around was good enough to go second, despite pulling all kinds of shapes to do it.
Looking to relegate Mir and Rins off the top two spots, Marquez and Miller were both on absolutely brilliant laps.
Marquez fell short in the final sector, but Miller did not as he went top.
But just as Miller looked to have taken FP2 honours, Zarco went a further two tenths quicker,while fellow countryman Quartararo also leaped up from 11th to third.
Bastianini managed to keep hold of fourth late on, while race favourite Rins and Marquez were fifth and sixth respectively. A. Esprargaro was the first rider to miss out on a top ten in 11th.