Andrea Iannone led Danilo Petrucci in second MotoGP practice for the Australian Grand Prix, while early pacesetter Cal Crutchlow was stretchered off track after a fast fall in the closing stages.
Top spot changed hands continuously across the 45 minutes, with Iannone putting his Suzuki at the head of the pack several times before putting a decisive 1:29.131s on his final lap.
Top three finisher this morning, Pramac's Danilo Petrucci set the benchmark in FP2 with a 1:31.505s, though this was quickly bettered by Marquez.
Andrea Iannone shadowed the Honda rider across the line and took over instantly with a 1:30.256s, before Andrea Dovizioso went fastest by just under two tenths.
FP1 faller Marc Marquez set the best lap of the day so far 10 minutes into the second session with a 1:29.739s, though came close to another crash moments later when he had a rear end moment into Siberia and was forced into the gravel.
Honda stablemate Crutchlow edged ahead at the top of the timesheets with a 1:29.616s, but the LCR rider was soon deposed by Iannone once more, who went just over a tenth faster than the Briton.
Crutchlow's session ended prematurely when he suffered a fast crash a the Doohan corner with 12 minutes remaining, and had to be stretchered off circuit. He is currently in the medical centre undergoing checks.
Having gone second and missing top spot by just 0.045s, Dovizioso moved his Ducati ahead of Iannone on the timesheets with a 1:29.406s with four minutes remaining.
Dovizioso's time at the head of the standings was brief, as Ducati stablemate Petrucci deposed him with a 1:29.291s, while FP1 pacesetter Maverick Vinales slotted into second having gone top just prior to Petrucci.
Iannone lit up the timing screens on his final tour and fired in a 1:29.131s to secure top spot by over a tenth from Petrucci, while Vinales completed the top three.
Dovizioso found himself fourth in the end from Crutchlow, who held fifth despite his crash. Johann Zarco completed the top six on the Tech3 Yamaha, while Marquez was a low-key seventh at the end of FP2.
Home favourite Jack Miller was eighth fastest on the second Pramac Desmosedici, with Alex Rins [Suzuki] and Valentino Rossi rounding out the top 10, with Rossi's Yamaha stablemate Hafizh Syahrin [Tech3] just a few hundredths outside of the Italian's time in 11th.
Alvaro Bautista's second session as Jorge Lorenzo's replacement proved disastrous, as an early crash at Siberia and a technical issue with his second GP18 meant he only completed five laps and was 15th.
Takaaki Nakagami compounded a nightmare few minutes for the LCR team, when he crashed at Siberia not long after teammate Crutchlow went down. The Japanese rider was unscathed, however, and was 18th as a result.
