The glory will go to Trent Boult with his devastating bowling and Brendon McCullum for his leadership but Williamson showed real metal in steering the ship home. That vessel had hit an iceberg way nastier and unexpected than the one the Titanic hit.
McCullum is a dead-set legend, too.
Watch: Black Caps win thriller against Australia - highlights
It was a day for legends, actually, with an emotional induction into the ICC Cricket of Fame for Martin Crowe. Never has a day or occasion been more appropriate for such a presentation than at Eden Park against Australia in the World Cup.
This was the scene where, 23 years ago, Crowe sensed the occasion and scored a century against a very good Australian side to set the tone for the 1992 World Cup campaign.
McCullum now appears to possess that same sense of occasion that make good players - players of legend.
McCullum seized the day against Sri Lanka in the tournament opener, then came to fore in the win against England making the statement he wanted. In yesterday's game he was 'The Little Master'.
Williamson sensed the occasion as well and it will be a fun debate in years to come to decide who will be our greatest ever cricketer.
McCullum and his boys showed composure under fire when Aaron Finch and David Warner opened up and the decision to bowl Daniel Vettori in an uncustomary early role showed a leader who can think clearly under any circumstances.
The way he worked his main three bowlers to carve a swathe through the powerful Australian batting was masterful. Then his hitting at the top of the run chase put his indelible stamp on the day.
What a game. Forget the poor shots, the low scoring, this was a high-quality game of pressure cricket.
It could be some time before we are entertained like this again.
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