Edwards had been second fastest to Stoner on race tyres less than a week ago at Sepang, but hit the top on the opening day 'down under' after a best time of 1min 29.5secs with the aid of super-soft specification Michelins.

The Texan had been left frustrated after failing to find any additional speed on qualifying tyres at Sepang, but had claimed he knew how to solve the problem - and will surely have been pleased to lap just 0.3secs behind Dani Pedrosa's pole position time at last October's grand prix.

"It was a good day,2 declared Edwards. "I started with the same setting I finished in Malaysia and played around with that for the day. The bike feels good at this track compared to what I raced with a few months ago. Yamaha has been working hard and the new parts are definitely a step in the right direction, particularly with the electronics, which has helped on corner entry and exit.

"With a qualifying tyre in Malaysia my time didn't get any better. I had a couple of handling issues with the qualifier in Sepang so once I got a good pace going I chucked a couple of qualifiers in. It is the first day but you never know what the weather is going to do down here, and it could be raining tomorrow. We wanted to make sure with the adjustments we were going to make for the qualifier that it was the right way.

"In Sepang I had too much weight on the rear. The rear was taking over and running me wide and we made a change to get more weight on the front and get it to turn a bit better. It seemed fine and I'm happy with the lap time," added Edwards, whose best race lap was a 1min 30.832secs.

Pedrosa isn't present at Phillip Island due to his fractured hand, while the factory Fiat Yamaha Team is also absent. Nevertheless, Valentino Rossi - and particularly fellow Michelin rider Jorge Lorenzo - will have been buoyed by Edwards' pace and also encouraged to see the American's rookie team-mate James Toseland (a WSBK race winner at Phillip Island) in the top five (+0.65secs Stoner).

But Stoner's 1min 30.178secs on race tyres is already 0.7secs faster than he'd recorded en route to victory in the 2007 Australian Grand Prix and the #1 will surely take some catching over the next two days.

"Everything went really well today, the feeling with the bike was perfect almost straight away," said Casey. "The new Bridgestones, which had already given us positive feedback at Sepang, also worked perfectly here at Phillip Island - one of them in particular improves the bike a lot in the exit of the corners, especially in the final section of the track.

"We've also taken a step forward with some small changes to the front, which have made the bike more stable and improved grip to the point where my best time came without pushing, on a tyre that already had 17 laps on it. I'm also really happy with the latest specs of the engine and the way it is responding under acceleration coming out of the corners.