In the words of captain Ricky Ponting [Images], Australia have their "backs to the wall" following a shock defeat by Zimbabwe on Wednesday and the world champions must beat England to stay alive in the inaugural Twenty20.

England are assured of qualification for the next stage unless they lose to Australia by more than 50 runs and Kevin Pietersen [Images] is relishing the challenge ahead.

"We were humiliated by Australia (in the Ashes) last winter and now we're in a position of strength where we can pretty much humiliate them," Pietersen said following his man-of-the-match knock of 79 from 37 deliveries.

"It's somewhere we haven't been for a long time and it would be a really good day for England if it happens. I'm not saying it is going to happen but it's an opportunity of a lifetime," Pietersen said.

Ponting admitted he was embarrassed by his team's performance against the African nation and knows they have to improve drastically if they are to prolong their stay in South Africa.

"We're playing a good team and we're going to have to play a lot better than we did against Zimbabwe if we want to win," Ponting said.

"We have to improve, it's as simple as that. There's a short turn around between games but I'm hoping it's more a mindset thing that we have to get right."

Playing against the 'old enemy' usually brings out the best in Australia and Ponting expects his team to rise the occasion again.

"It wasn't long ago that we played a lot of cricket against England, in both forms of the game, but having said that they have the edge on us in experience in Twenty20 cricket -- we're all still very new to it.

"We have to learn from our mistakes (against Zimbabwe) and if we don't then we're fools. Hopefully we can bounce back on Friday."