England captain Michael Vaughan hailed Kevin Pietersen as "a genius" as his stunning innings heaped more misery on Australia in the NatWest One-Day Series at Bristol.
Pietersen rescued England, as their innings was beginning to stumble in pursuit of a target of 253, with an explosive 91 not out off only 65 balls.
The Hampshire batsman hammered eight fours and four sixes as England triumphed by three wickets with 15 balls to spare.
Australia have lost four one-day matches in the last seven days and they were powerless to stop the assault on Michael Kasprowicz and Jason Gillespie by Pietersen.
Vaughan said: "It is very pleasing when you play Australia and play well against them and you want to make sure that you get across the finishing line.
"That innings by Pietersen is special, very special.
"He has played some great knocks and he has been in the team for only a short while but he was in a pressure situation of playing Australia and he did so well.
" He knew that, once Vikram Solanki got out, he was basically down to the bowlers and he had to see us home and to do it under that sort of pressure is fantastic.
"How good an innings is that? It is very difficult to say but, from an England player, I haven't seen any better.
"To restrict Australia to 250 on a good wicket, we were delighted about that.
"I don't think we chased too well, to be honest, apart from this man (Pietersen) - a genius.
"To get 91 off 65 balls like that is a fantastic innings."
The Yorkshire batsman continued: "We lost wickets at crucial periods.
"We shouldn't have let a good side like Australia back in the game like we did on two or three occasions but we still got home, so that is a huge positive we can take.
"We were outstanding in the first half of the match. Steve Harmison's spell [with three wickets in four balls] certainly changed the game, plus Paul Collingwood's catch to get rid of Matthew Hayden.
"Little moments like that change the outcome of matches and that certainly went a long way towards us winning.
"I thought all the bowlers in little periods bowled very well on a good wicket." Pietersen has a staggering average of 162.25 in one-day internationals and he was quick to play down a verbal spat with Australian bowler Shane Watson.
He said: "It was just competitive cricket, it is a heated game.
"Playing Australia is a huge challenge. I challenge myself against the best side in the world and it was fantastic.
"Both of us were pumped up. It was a do-or-die situation. I think we needed 50. If they had got me out, it was probably game over.
"He was playing hard for his country and I was playing hard for mine.
"We had an exchange but we are going to be teammates [at Hampshire] in a month's time, so it was just part of the game."
Pietersen came to the wicket with England struggling at 119 for four in the 28th over but a half-century stand with Solanki, the Worcestershire batsman, and some solid resistance from Jonathan Lewis at the death saw England home.
He said: "I never thought we had lost it at any stage. The boundaries are small at Bristol and I knew that if I had batted for another 15 overs, we would get close.
"I never thought we were out of it, not even when Jon Lewis came in. I didn't think they had the firepower to knock him over. I asked him to play nice and straight and there was a run every time and he batted brilliantly. I take my hat off to him because the job he did was fantastic.
"It was only his second oneday international - and for him to do what he did against Australia was fantastic."
Australia captain Ricky Ponting took plenty of positives from his side's improved showing despite ultimately suffering another setback.
He said: "I thought there was a lot of improvement today. We were winning the game for a lot of our bowling innings and disappointed not to win the game in the end. But I was very satisfied with the way we batted through the middle of our innings and we posted a total which I thought was defensible.
"The first 35 overs when we bowled was very good. We stumbled a bit at the end but there was some good batting which went England's way.
"Kevin Pietersen batted beautifully at the end and led England across the line. Overall, I was disappointed to lose but there were some signs for us today of going forward."