Australia were mugged by twin hundreds from Somerset's overseas opening pair Sanath Jayasuriya and Graeme Smith as the tourists' tricky start to their 2005 Ashes summer continued with a shame-faced defeat at Taunton on Wednesday.

On a belter of a pitch, it appeared the Australians had done all they could to banish the memory of their Twenty20 mauling at England's hands by piling up 342 for five in their final warm-up match before the NatWest Series.

But it was soon patently clear that even Australia's pace pairing of Glenn McGrath and Brett Lee had little answer if talented batsmen got going - and by the time Smith (108) and Jayasuriya (101) had combined in a stand of 197 off only 23 overs, Somerset had done the hard work.

The left-handed pair each needed only 42 balls for a half-century, Smith moving to three figures in another 26 and Jayasuriya needing 35. The South African hit 17 fours and a six, and there were nine regulation and three maximums for his Sri Lankan partner.

They flayed McGrath and Lee, who went off with a shoulder problem, to all parts in a devastating display which must have done as much if not more to dent famed Aussie confidence as their 100-run reverse against England at the Rose Bowl two days ago.

Smith eventually got greedy and was stumped off Michael Clarke's slow left-arm, and McGrath got rid of Jayasuriya - hooking to long-leg - when he was brought back early in an increasingly frantic search for wickets.

After McGrath had doubled up by bowling youngster John Francis round his legs and the might of Ian Blackwell foundered to a chop-on off Shane Watson, the margins began to favour Australia again.

But the likes of 20-year-old James Hildreth had just enough left in the significant absence of Lee and with rain threatening to get home with four wickets and 3.1 overs to spare.

The continued suffering of bowlers of all kinds put Australia's innings into better context and emboldened the question-marks over the retirements of Matthew Hayden (76) and Ricky Ponting (80) - whose decision to call it quits soon after reaching half-centuries seemed initially to border on contempt for opposition bereft of the services of their injured former England pace bowler Andrew Caddick but in the final analysis looked more ill-advised than rude.

The defections nonetheless had the desired effect of giving others in the Australian order a chance of time in the middle before their first one-day international of the summer, against Bangladesh at Cardiff on Saturday.

Hayden began proceedings appropriately by striking the first ball of the day for four past extra-cover off Gareth Andrew, counting the first of his tally of 12 boundaries in 53 balls of brutality.

Simon Katich was Hayden's largely silent opening partner in a stand of 60 which was broken by the last ball of the 10th over when the former lost his patience and holed out to cover, having gone on the charge to Simon Francis.

Hayden was therefore joined by Ponting, returning to an old haunt following his short stint with Somerset last summer.

It was the Queenslander who continued to make the pace, though, driving fearsomely on the up in all directions and pretty merciless too on anything dropped short.

Hayden has already been in ominous form so far this Ashes summer, with a century and a Twenty20 50 already under his belt from only three previous innings. But shortly after another half-century was safely in the book, he retired apparently well-satisfied with his early-season health to be replaced by Damien Martyn.

Ponting was by comparison circumspect over his 75-ball 50 - hitting only three fours - but celebrated with successive leg-side sixes off Smith's off-spin and then folded after another maximum over long-on off Andrew.

Martyn had already done enough to demonstrate his well-being before he was stumped trying to join in the barrage against Smith.

Australia therefore simulated a minor crisis by forcing Clarke (63no) and Mike Hussey (51) together without a run to their name, the result being some meaningful match practice for both and a brief cessation of embarrassment for the hosts - until 104 more runs were plundered in the last 10 overs.

Three hours later, however, everyone - the Australians, in particular - was much wiser about what is a safe score at Taunton.