Pietersen and Ambrose revive England
It was an invaluable performance from Pietersen, a man whose love of a sticky situation borders on the masochistic. After losing the toss and being asked to bat first by New Zealand, England batted with the looseness that has become a characteristic of the top six in recent matches. Alastair Cook and Michael Vaughan fell cheaply in the first hour, and though Pietersen and Andrew Strauss carried England to a comfortable 84 for 2 at lunch, the biggest meltdown was yet to come. In the space of 18 balls of the resumption, England lost three wickets for two runs - including both their under-pressure batsmen, Paul Collingwood and Ian Bell, for ducks.
It was a situation reminiscent of England's morning collapse in Napier - 4 for 3 had been the scoreline on that occasion - and then as now, Pietersen's response was to grow in stature to match the adversity. He had done his hard work in the morning session, defending with big watchful strides and leaving Strauss to pick off the bulk of the runs in a deftly compiled 37. After the break, however, when Strauss fell without addition, Pietersen eased through his gears and began striking the ball at the top of the bounce with all his familiar confidence.
He brought up his fifty from 106 balls with a hockey-style swipe through midwicket off Vettori, and his century followed 88 balls later with a crunching drive through the covers off the disappointing Chris Martin, whose final figures of 12-1-61-0 epitomised New Zealand's lost opportunity. It was the slowest of Pietersen's 12 hundreds, which was a testament to the tough conditions, but once he'd decided to make this his day, the majesty of his attacking strokes took the breath away.
He could not have turned England's innings around, however, without superb support from Ambrose, who produced his sparkiest effort since his maiden Test hundred in Wellington in March. Then as now, he used his lack of height as an asset, getting inside and underneath New Zealand's off-stump offerings and whipping out the uppercut whenever they dropped short. The only man who consistently plugged away on a decent length was O'Brien, who was surprisingly retained ahead of the rookie Tim Southee, and it was he who ended Ambrose's stay via a thin nick in the 87th over of the day.
In truth, both Ambrose and Pietersen fell in disappointingly tame fashions - Pietersen to a half-conceived dab to the keeper - but they were not alone in that. It was swing allied to poor technique that accounted for each of the first five England wickets to fall, as Vettori gambled at the toss by choosing to bowl first, and was - at first - well rewarded for his boldness. Since the erection of the new £8.2 million Bridgford Road stand, the highest first-class total at Trent Bridge has been a measly 279, and even after a Pietersen masterclass, England have not yet exceeded that effort.
For the first hour, the ball manoeuvred as if on a damp deck at Headingley, and Cook - whose technique outside off stump has long been under scrutiny - was unable to survive. He hung a limp bat out to Kyle Mills, and left enough space between bat and pad for the ball to crash off an inside-edge into his leg stump. One delivery later, and Michael Vaughan might have gone as well, as Mills produced the most superb ball of the session - a fizzing legcutter that beat both the edge and the top of off stump by a whisker.
Vaughan's response was elegant and aggressive. He laid into Martin with three fours in four balls, but no sooner had he got himself set, he was gone, as O'Brien tempted him into one drive too many, and clean bowled him for 16 from 22 balls. It was, however, a useful lesson to those that followed. Scoring opportunities were on offer in spite of the conditions, but watchfulness was of the essence. Bell and Collingwood failed to heed the warning, but Pietersen and Ambrose did not miss out. As a consequence, England are well placed to press home an authority that they once again looked to have squandered.
Andrew Miller is UK editor of Cricinfo