It was not one of Martyn's most fluid centuries

Damien Martyn scored an unbeaten 106 as Australia made 337-5 on day two of the second Test against New Zealand.

After a day's delay because of rain, NZ won the toss and openers Matthew Hayden (61) and Justin Langer (46) put on 82.

Daniel Vettori (2-74) and James Franklin (2-94) helped reduce the tourists to 174-4 before Martyn and Simon Katich (35) stepped up the pace.

Adam Gilchrist continued the onslaught with seven fours and a six in his rapid 45 as Australia ended the day on top.

Kiwi captain Stephen Fleming had no hesitation in opting to field in conditions ideal for seam and swing bowling.

But while Martin found a good line, Franklin struggled bowling into the wind in his opening spell.

Vettori made the breakthrough, however, when Langer - who was dropped on nought by Fleming off Martin - attempted a sweep and the ball ballooned off his gloves to wicket-keeper Brendon McCullum.

It could easily have been a different day Damien Martyn More reaction

The spinner struck again in the third over after lunch when Australian captain Ricky Ponting was trapped leg before.

Hayden, who had patiently moved on to 61, played a rash shot off Franklin and was caught at cover by Lou Vincent to leave Australia at 146 for three.

Michael Clarke struggled for fluency and soon followed when Nathan Astle found his edge and Fleming made no mistake this time.

With Martyn initially scratching around for runs, New Zealand were right back in it at tea.

But the arrival of the second new ball sparked a turnaround, and Martyn and Katich stepped up a gear to put on 84 for the fifth wicket.

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After his nervous start, Martyn flourished to complete his 12th Test century off 173 balls.

There was one success for New Zealand in the post-tea session, Katich (35) edging Franklin behind - but then the fireworks really began.

Martyn and Gilchrist punished some loose bowling to race to a 50 partnership in just 29 minutes, as the tourists added 163 in the day's final session to take a firm grip on the match.

New Zealand: S Fleming (capt), C Cumming, H Marshall, L Vincent, N Astle, C McMillan, B McCullum (wkt), D Vettori, J Franklin, I O'Brien, C Martin.

Australia: R Ponting (capt), M Hayden, J Langer, D Martyn, M Clarke, S Katich, A Gilchrist (wkt), S Warne, J Gillespie, M Kasprowicz, G McGrath.