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A day which dawned with humbling defeat high on the agenda, will instead go down as one of the most memorable in New Zealand test cricket history.
Especially if the Black Caps can kick on tomorrow and bowl their way to what would be one of the most improbable test wins of all time.
New Zealand went to stumps at 571 for six, having begun the day at 252 for five
They will resume tomorrow 325 runs ahead with McCullum unbeaten on 281 and Jimmy Neesham on 67.
BJ Watling's was the one wicket to fall on another quality day of cricket in which the one constant was McCullum.
It's a long shot that New Zealand can bowl India out to tomorrow or if they'll even try.
That it's even a consideration or that they now look like, at worst, they'll draw and win the series 1-0 is largely down to one man.
To bat on grimly for almost an entire day of test cricket is one thing, especially when, in McCullum's case, you're a player who expresses his talent through expansive shots.
But the idea that the New Zealand captain could do it all again today seemed fanciful.
History has shown the man is simply too free, too keen to dominate, too much of a gambler and hunch taker to tie himself down too long.
He said the situation had required it on day three, so he had. But today loomed as being a different story.
Well, how wrong could you be?
Instead McCullum played with similar restraint and responsibility, going on and on until he'd played the longest innings in New Zealand test history.
He set a slew of other marks along the way; either on his own or as part of the highest test partnership for the sixth wicket of all time, with Watling.
That was some feat in itself, with Watling finally out for his highest test score of 124.
Only McCullum wasn't done. Obviously weary and troubled by various niggles, the captain willed himself further still, posting a century partnership with Neesham and taking the team past 550.
Think of some of the words that have been used to describe McCullum by various detractors over the years.
Those descriptions have no place being mentioned here and, hopefully, won't be uttered ever again.
In the first test at Eden Park, and now here, McCullum has played innings' of the highest calibre in situations when his team badly needed them.
The Auckland knock was more typical of his career, with buccaneering moments and runs coming at a good clip.
But this Basin innings has to be described as extraordinary. Maybe even career-changing.
The old assumptions about McCullum don't apply anymore. There'll still be times when he frustrates fans or sells himself short, but fighting double hundreds in consecutive tests are only scored by special players and these last two days of batting at the Basin move McCullum into a different echelon of New Zealand test cricketer.
Day four of the second test at the Basin Reserve, Wellington:
First innings 192
Second innings (252-5 overnight)
P Fulton lbw b Zaheer 1
H Rutherford c Dhoni b Zaheer 35
K Williamson c Dhoni b Zaheer 7
T Latham c Dhoni b Shami 29
B McCullum not out 281
C Anderson c and b Jadeja 2
B Watling lbw b Shami 124
J Neesham not out 67
Extras (b 5, lb 11, wd 2, nb 7) 25
Total (for 6 wkts, 189 overs) 571
Fall: 1, 27, 52, 87, 94, 446.
Bowling: I Sharma 39-4-124-0 (6nb), Zaheer Khan 43-12-129-3 (2w), M Shami 40-5-136-2, R Jadeja 49-10-108-1, R Sharma 11-0-40-0, V Kohli 6-1-13-0 (1nb), M Dhoni 1-0-5-0.
First innings 438
- Fairfax Media
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