Jorge Martin topped the timesheets in Friday's opening free practice for the Australian MotoGP, with championship leader Francesco Bagnaia lagging in 11th.

On a fine day, the Pramac rider blitzed the picturesque Phillip Island circuit with a best lap of one minute and 29.039 seconds.

The Spaniard, who sits second in the overall standings -- 18 points behind reigning world champion Bagnaia -- was 0.720 quicker than second-placed Augusto Fernandez, with Maverick Vinales third and Brad Binder fourth.

Italy's Bagnaia was 1.479 adrift on his Ducati.

Martin won last weekend's sprint race in Indonesia, but crashed in the grand prix while leading to hand the championship advantage back to Bagnaia, who went on to win.

In a change of format since the mid-season break, the first practice session now has no bearing on Saturday's qualifying order, leaving riders and teams to try out different bike and tyre set-ups without consequence.

The top 10 times from Friday's second hour-long practice will automatically go through to Saturday's main qualifying.

This group will be joined as usual by the fastest two riders from Q1 to determine the first five rows of the grid both for Saturday's sprint race and Sunday's main event.

Four-time Australian winner Marc Marquez was the first faller of the weekend, losing his front end while braking at turn 10.

Fellow Spaniard Alex Rins, last year's winner at Phillip Island, also came to grief, sliding into the gravel.

Rins, who competed last week for the first time since fracturing his leg in May, appeared to be limping as he walked away.

mp/smw