What could have been a great day for the New Zealanders in the second National Bank Test against Pakistan in Christchurch lost some of its lustre in the last session when a vital catch was dropped.

Still on a high after 25-year-old Mathew Sinclair's achievement in scoring a second double century, 204 not out, in his 12-test career, New Zealand had Pakistan reeling at 25/2, which should have been 42/3 but for a dropped catch by second slip Nathan Astle.

Inzamam-ul-Haq, just back from a groin injury, was on 10 when he edged a catch to Astle, who in normal circumstances would have swallowed the chance, but who is anything but the natural player he has been, and he managed to let the opportunity slip.

For a side which earmarked a fatal dropped catch of Younis Ahmed as the losing of the first Test in Auckland, it was a bitter sweet moment and one they will be looking to put behind them when Pakistan resume tomorrow on 65/2.

But it was Sinclair's day. His was a superb innings, a mixture of applied concentration and forthright disposal of hittable balls.

He started the day on 100 not out, and another 275 minutes and 187 balls later, he walked from the ground with New Zealand 476 all out and unbeaten having joined Glenn Turner as the only New Zealanders to have scored two double centuries in Tests.

Sinclair acknowledged the support of his team-mates who managed one of the more consistent innings of the summer.

He did have the rare advantage of starting his innings with the New Zealand openers having put 100 runs on the board. And he made the most of it.

The new ball wasn't as fresh as it has been in his most recent outings and it offered him some comfort as he began his innings.

"I have been very conscious of playing the vee. I hit it a heck of a lot straighter, but they bowled some pretty good channels," he said.

Sinclair said he enjoyed an interesting tussle with off spinner Saqlain Mushtaq.

"He is an amazing bowler. You can't help but admire anyone who can bowl a mystery ball like he does. It is different to anything I've ever faced before.

"I still found it hard to try and pick the ball.

"It was a good challenge and I got one back at him, I told him 'If you can teach me to bowl the other one, I'll teach you how to bat,'" he said.

Sinclair did show outstanding concentration in coming to grips with Saqlain's other ball and especially as he started running out of partners with only the ill-equipped lower order batsmen left.

With the worst No 11 batsman in the world, Chris Martin, with him at the crease, Sinclair looked like being stranded on 196 but Waqar Younis managed to miss the wickets for three balls in succession and Sinclair had his chance.

"I think I fooled him a little. They brought the field in and he bowled one short of a length on leg stump and I picked the right shot," Sinclair said.

It went for six over square leg, the shortest boundary on the ground to take him to 202.

Sinclair said the response of the side after the humiliation in Auckland had shown the gutsiness Kiwis show after they had been knocked down and wanted to get back up again.

Certainly he had good support today with Craig McMillan helping him add 45 runs for the fifth wicket while Adam Parore scored 46 as 101 runs were added for the seventh wicket.

"I guess it is about patience. It is great as a batsman to wear fast bowlers down," he said.

Saqlain bowled well throughout, constantly testing the batsmen and had his reward with 3-134. Fazl-e-Akbar took 3-87 while Waqar's tidying up of the tail ended with him having 3-114.

The full list of New Zealand's double century makers in Test cricket is:

Martin Crowe      299   v Sri Lanka     Wellington     1990/91
Bryan Young       267*  v Sri Lanka     Dunedin        1996/97
Glenn Turner      259   v West Indies   Georgetown     1971/72
Graham Dowling    239   v India         Christchurch   1967/68
Bert Sutcliffe    230*  v India         New Delhi      1955/56
Glenn Turner      223*  v West Indies   Kingston       1971/72
Mathew Sinclair   214   v West Indies   Wellington     1999/00
Martin Donnelly   206   v England       Lord's         1949
Mathew Sinclair   204*  v Pakistan      Christchurch   2000/01