Quickest rider
This left Marquez ending the day as the quickest rider, with a P2 for the 2018 world champion in the second session to cap off a good day, and Miller P2 despite finishing P13 in FP2.
Petrucci topped FP1 by a significant margin - 0.407 was the gap back to the number 93 - with Valentino Rossi (Movistar Yamaha MotoGP) the only other rider within a second of the Ducati rider in the second session.
'The Doctor'
It was P12 overall for ‘The Doctor', however. Andrea Dovizioso (Ducati Team) sits fourth overall and the Italian was P12 in FP2.
Dani Pedrosa (Repsol Honda Team) completed the top five on Day 1 despite conditions that have often been more difficult for the newly-inducted Legend this season.
Fastest Yamaha
Andrea Iannone (Team Suzuki Ecstar) - fourth in FP2 - ended P6 on the combined times, with Maverick Vinales (Movistar Yamaha MotoGP) ending the day as the fastest Yamaha rider in P7 overall.
Wildcard and Ducati Team test rider Michele Pirro sits P8 overall thanks to his FP1 time, a strong showing for the Italian, as Red Bull KTM Factory Racing's Pol Espargaro grabbed a provisional Q2 spot.
Wet conditions
A P6 in FP2 - along with team-mate Bradley Smith's P8 - capped off a good day for the Austrian manufacturer in the wet conditions.
Alex Rins (Team Ecstar Suzuki) rounded out the top ten, but just 0.002 ahead of compatriot Aleix Espargaro (Aprilia Racing Team Gresini) in P11.