Pietersen is averaging 67.0 in the series so far

England trail 2-0 in the five-match series and hard-hitting batsman Pietersen says the team have no choice but to go all out for victory in Perth.

"We'll be going out with all guns blazing knowing we've got to play positive cricket and we've got to win this Test match," said Pietersen.

"We know what we've got to do this week - it's crunch time."

Interview: England batsman Kevin Pietersen

Pietersen said the team had been at full throttle during nets sessions as they try to retain the Ashes.

"We know that this week is a huge, huge week for us. We definitely don't want to be here next week talking about being 3-0 down in the series," he said.

"Our training session showed that we mean business.

"The boys have been put through their paces massively and from the first ball that was bowled in the nets this afternoon it was 90mph-plus."

England have yet to reveal their team plans but the claims of spinner Monty Panesar, paceman Sajid Mahmood and wicket-keeper Chris Read are all likely to be discussed before a final XI is chosen.

606: DEBATE Pietersen has been one of the few positives of the tour, along with Collingwood and Hoggard UD 606: Have your say

Pietersen, meanwhile, is looking forward to renewing his rivalry with leg-spinner Shane Warne, who needs only six wickets to reach 700 in Tests.

Warne, who is expected to play despite hurting his elbow in practice, bowled Pietersen during England's dramatic final day collapse in the second Test at Adelaide.

"It was a great ball which pitched outside leg stump and hit my off stump and there's nothing you can do about it but just say he's the greatest bowler that's lived.

"I've always enjoyed facing Shane and I'll enjoy facing him this week. but hopefully it will last longer than one ball," Pietersen commented.