Massa was the quickest race driver in Malaysia on Friday

Zonta set a lap of one minute 34.092 seconds in the first session to head McLaren test driver Pedro de la Rosa by more than a second.

Sauber race driver Felipe Massa set the pace in the second session with a lap quick enough to put him third overall.

McLaren's Juan Pablo Montoya was the fastest of the recognised pace-setters, with fourth fastest lap overall.

The Colombian's time was second fastest behind Massa in the second session, when Montoya was 0.09secs ahead of team-mate Kimi Raikkonen.

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Montoya said: "We have been working on the balance of the car trying different things to see what works for me, and we are going in the right direction.

"It was quite slippery out there because of the heat, but I didn't experience any problems. We definitely have the pace and now we need to make it work when it matters, which is on Sunday."

Montoya was fastest of the recognised pace-setters on Friday

Ralf Schumacher's Toyota was next quickest, followed by Australian Grand Prix winner Giancarlo Fisichella's Renault and the Ferrari of Rubens Barrichello.

Barrichello's team-mate Michael Schumacher was next fastest with a time set in the first session.

BAR driver Jenson Button, who finished a disappointed 11th in Australia, was fifth and eighth fastest in Friday's two sessions and encouraged by his team's performance.

Button said: "I'd be very impressed with a podium - I think that's a bit too much to ask at the moment.

"If we achieved that then we have achieved a lot more than we thought possible at this time of the year."

The new rule demanding engines last for two races as ensured race drivers do as little mileage as possible on Fridays to limit wear on their cars.

That means times in Friday practice can be poor indications of form for the rest of the weekend.