Reigning MotoGP world champion Marc Marquez has upstaged title challengers Jorge Lorenzo and Valentino Rossi to post the fastest time in the second practice session at the Australian Motorcycle Grand Prix.

Lorenzo was quickest in the first practice on Friday on his Movistar Yamaha, with Marquez posting the second-fastest time.

But the Spanish Repsol Honda rider turned the tables on his countryman in the afternoon session with a blistering late run.

“Today was a good day – I enjoyed it and we improved the set-up, which is most important,” Marquez said.

“We did the correct steps and precisely, which is not easy.

“But I think tomorrow we must improve a lot because it looks like the Yamaha riders – especially Jorge – their rhythm is really fast, so we will keep working hard.”

Rossi posted the third-quickest time in the cool morning practice that ended early as a shower passed over the Phillip Island circuit but the Italian master dropped down the rankings in warmer conditions in the afternoon with the ninth-fastest lap.

With three races to go in the MotoGP championship, Rossi holds an 18-point lead over Yamaha teammate Lorenzo, with Marquez a distant third.

Jack Miller was the best of the local hopes with the Queenslander posting the 11th fastest-time on his LCR Honda.

“(The bike) looks good. We went a little bit quicker in the afternoon than we did in the morning, so I’m happy with that, but I’m definitely looking forward to trying to improve tomorrow,” Miller said.

“We’ve got a few areas of the bike that we still need to work on.”

A third practice session takes place on Saturday morning with the top 10 riders on aggregate across all three sessions going through to second qualifying.

They will fight it out for pole position, while the remainder of the field will try to get as far up the grid as they can in first qualifying.

The remaining Australian riders, injury replacements Anthony West and Damian Cudlin, are at the bottom of the rankings after the first day’s practice with the 24th and 25th best times respectively.

West is riding for AB Motoracing in place of Czech Karel Abraham, while Cudlin is on an IodaRacing Team bike after Alex de Angelis suffered serious head and chest injuries in last week’s Japanese MotoGP.