The unheralded Frenchman, a lowly 16th in the championship standings, lapped the 4.44km Phillip Island circuit in one minute 29.745 seconds to edge Italy's Loris Capirossi on a Ducati into second on 1:30.310.

De Puniet's time, set just moments before the end of the session, was the fastest time of the day after Capirossi had earlier topped the times in first free practice.

World championship leader Nicky Hayden of the United States was third quickest, 0.726secs behind de Puniet, with main title rivals Dani Pedrosa, his Repsol Honda team mate, and Yamaha's world champion Valentino Rossi in 16th and sixth places.

Hayden leads the championship with four races to go by 22 points from Spaniard Pedrosa, who hobbled to his bike clearly still troubled by the leg injuries picked up during a crash in practice for last week's Malaysian GP.

Italy's Rossi lies third in the standings, 26 points behind Hayden.

Italian Marco Melandri, who along with Capirossi is the only other rider with a mathematical chance of clinching the title, finished the second session in eighth position having failed to improve on his morning time.