Foggy Petronas riders Troy Corser and Chris Walker found themselves locked in intense battles throughout Sunday's two races at Australia's Phillip Island circuit.

Race one saw Walker leap into an excellent fifth by the end of the first lap, and was forced to ride the wheels off his FP-1 to overcome the machines lack of top speed along the home straight.

Nevertheless, it would be horsepower that cost 'The Stalker' a further five places by the chequered flag, the Brit only losing ninth on the race to the finish line.

"I got a great start, which is what I needed from the third row, and it was a shame that the bike lost a bit of ground going onto the start finish straight as I could match the others just about everywhere else," he admitted.

"I rode a bit defensively on the last lap because I could hear Chili's Ducati behind me but I was always struggling for speed down the straight without someone in front of me so there was nothing I could do to stop him coming past. I am reasonably happy to finish in the top ten."

Meanwhile, home hero Corser was left a disappointing 13th after his three-cylinder engine overheated.

"The bike was over-heating straight away and was pretty inconsistent. I saw some oil midway through the race and lost a few seconds when I overshot going into Honda on lap 13 because of that," he explained.

Race two would prove much more fruitful for the Aussie as he took advantage of the opening lap chaos to jump up the order, and then put up a spirited defence against his more powerful rivals behind him. Corser would eventually finish an excellent fifth, in front of Valencia winner Noriyuki Haga.

"It was really good to be dicing again and I enjoyed that race," said Troy. "At the start of the race two bikes came together and forced a few riders out wide and I was able to dive through the gap.

"For the rest of the race the other bikes passed me down the straight but I was able to re-pass them through the corners at the back of the circuit," he explained. "I thought Haga was going to pass me at the end but I was a lot quicker than he was through Hayshed and I tried to hold him up there and create as much of a gap as possible before the final section."

Team-mate Walker was left without a tow along the main straight and would finish a lonely eighth, taking valuable championship points for himself and Carl Fogarty's team.

"I got a really good start again but I was one of the riders who were pushed out wide at the second corner," he revealed. "After a couple of laps I ran wide at Honda and lost my tow so, after that I just had to get my head down and lap as quickly as I could and I did manage to set my fastest lap of the weekend.

"I was hoping for a bit better results but it was another good solid ride and I was happy to score more points for Petronas before the engine developments come later in the season."