Kevin Pietersen batted himself further into Ashes contention in the NatWest Challenge by thrashing by Australia - before injury put his hopes in some jeopardy.

Faced with the kind of crisis he has responded to so emphatically in his brief England career, the 25-year-old struck a majestic 74 at the Brit Oval to help the hosts post 228 for seven in their quest for a first piece of silverware against the Australians since 1997.

It was an innings in vain, however, as Australia cruised home by eight wickets with more than 15 overs to spare, their most decisive performance to date on this tour sealing a 2-1 win, a major psychological blow with the Test tussle beginning at Lord's next Thursday.

Whether Pietersen can edge out veteran Graham Thorpe in selection to make his debut has been the major point of debate and one fuelled further by the groin strain picked up while at the crease, which hampered him in the field.

He left the action at the end of the fourth over for ice treatment on the problem and did not re-emerge.

The selectors meet to pick the squad for the opening match on Wednesday, when the fitness levels of Thorpe will be discussed, presumably now alongside the well-being of Pietersen.

His influence earlier, along with that of substitute Vikram Solanki, who also struck a half-century after being thrust into the piece at the expense of pace bowler Simon Jones in the 28th over, ensured England recovered from a position of 93 for six.

Initially circumspect as his side's precarious position dictated, Pietersen broke into stride with a lofted six down the ground off spinner Michael Clarke, which Michael Kasprowicz carried over the ropes in completing a spectacularly agile catch.

Pietersen's half-century, his first since the match-winning, unbeaten 91 which saw off the Australians at Bristol at the beginning of seven limited-overs encounters between the teams, arrived in the 39th over, from 67 deliveries.

When he swatted a second maximum over long-on from in front of his face off a short ball from Jason Gillespie, in an over which cost 15, it appeared England might manage a more sizeable total.

But Gillespie quelled such hope in his next over, the final of his 10, when a slower ball foxed Pietersen as he fell to the leg-side.

He departed to a standing ovation, having doubled the score alongside Solanki, who adapted impressively to an unfamiliar role at number eight to hit an unbeaten 53, including a collection of handsomely struck cover drives.

The ease with which England's batsmen were able to play in the second half of their innings did not bode well, contrasting sharply to the questions posed by the new ball after Ricky Ponting won the toss.

As if to emphasise the change in conditions, Adam Gilchrist struck a scintillating hundred, the 11th of his one-day international career, dominating a first-wicket stand with the returning Matthew Hayden.

Four times in one Steve Harmison innings the ball seared to the rope, immediately after Hayden bullied Darren Gough for three boundaries.

Australia were already getting away from Michael Vaughan's men by the time Hayden offered a half-chance in the sixth over, sent down by Andrew Flintoff, which failed to be grasped by substitute Matt Prior low down at midwicket.

Having sacrificed Simon Jones, England required early wickets but the breakthrough did not arrive until the 16th over when Gough produced a full delivery which Hayden nicked.

If anything the tempo heightened, however, as Ponting joined Gilchrist in a stand of 94.

Gilchrist was particularly harsh on left-arm spinner Giles, striking two sixes through long-on, either side of reaching three figures from just 81 balls.

Ponting ominously caressed into gaps at the other end before giving the 23,000 crowd something to cheer about with a rush down the wicket which provided Giles with his solitary success.

Such was the thrill of the chase, however, that Vaughan did not engage his final two powerplays, a fact which magnified the margin of victory further.

By the end of the Australian innings, which culminated with a pull for four by Damien Martyn shortly before 6pm, Harmison was just shy of inheriting one of England's most ignominious records.

With one ball unused of his allotted 10 overs, Durham's Harmison was just two runs short of the most expensive return for an England bowler, the 83 runs conceded by Derek Pringle against the West Indies in the 1987 World Cup.

Such stroke-making contrasted heavily to the domination of ball the Australians exerted earlier in the day, having done so twice at Lord's within the past fortnight, has become a worry.

The tone was set by Glenn McGrath, who opened with four consecutive maidens from the pavilion end and whose first runs came when Vaughan hooked straight to fine-leg where Gillespie inexplicably floored a straightforward opportunity.

Gilchrist floored another chance from a spiralled pull from Andrew Strauss but Kasprowicz did for the latter and Andrew Flintoff by finding genuine edges and the previously out-of-sorts Gillespie found form at last with three for 44.

But for Pietersen's latest act of defiance, in fact, the guard of honour formed by both teams for retiring umpire David Shepherd at the finale might have come three hours earlier, a sobering thought with the main event of the summer now upon us.