Hobart: New Zealand ripped through Australia's batting line-up on a lethal wicket to leave the hosts foundering on 81 for seven in their first innings at lunch on the second day of the second test on Saturday.    

Peter Siddle, seven not out, and James Pattinson, who had yet to score, were at the crease with the hosts still 69 runs behind New Zealand's tally of 150 and needing 22 to avoid the ignominy of their lowest test score against the Black Caps.   

Chris Martin, celebrating his 37th birthday, bowled superbly on the lively greentop and took two wickets in the extended morning session to add to his one victim before rain washed away two hours' play on Friday.    

Resuming on 12-1, the Australians were looking to build up a big score but ended up scratching for runs as wickets fell with metronomic regularity.   

Opener David Warner was the first to go for 15, driving at a full Martin delivery but only managing to edge the ball to Black Caps' skipper Ross Taylor in the slips.   

Local favourite Ricky Ponting had accumulated five runs before Tim Southee trapped him lbw, a decision so clear the former Australia captain was walking back to the pavilion before the umpire's finger was raised.   

Martin again got plenty of movement off the wicket to claim his second wicket of the morning when Usman Khawaja, who had made seven off 51 balls, got a nick on an outswinger and wicketkeeper Reece Young took the catch.   

Trent Boult snared his first test wicket on debut to account for Mike Hussey, who was caught behind for eight, before wicketkeeper Brad Haddin smacked the ball to Brendon McCullum at mid-off from the bowling of Doug Bracewell for five.   

Michael Clarke, who made a century in Australia's nine-wicket victory in the first of the two tests at the Gabba, had survived an early lbw scare and made 22 when he became Bracewell's second victim.   

The Australia skipper suffered a momentary lapse of judgement and left a short inswinger only to see the ball knock his off-stump out of the ground.   

That left his side on 75 for seven and facing the real possibility of a first test defeat on home soil to New Zealand for 26 years.