A contest within a contest bloomed yesterday at the Basin Reserve: it was New Zealand versus Australia, but also Josh Hazlewood versus Kane Williamson.
Anxiety emerged in the Black Caps No.3's body language as he faced a bowler delivering such a challenging line. The pitch seemed to get extra tapping and his protective gear was subject to myriad adjustments.
Hazlewood bowled 17 balls at Williamson. Fourteen pitched in the corridor of uncertainty outside off stump.
The 10th of these in succession - the first ball of Hazlewood's 13th over - feathered an edge behind.
Williamson started the summer with some of the most sublime batting seen by an overseas player in Australia. His 140 at Brisbane, in a struggling New Zealand cause, had moments which required a sharp intake of breath, such was the technical perfection.
Likewise, his 166 in Perth, when New Zealand were staring down an Australian first innings of 559, earned respect from the most partisan of fans.
When Williamson is batting, fans are drawn with a gravitational force towards grounds, televisions and radios.
However, Hazlewood has struck a seam, as it were. Williamson looked to be concentrating harder than ever on a ground which, before yesterday, he averaged 210.5 batting second in five test innings.
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Since Perth, Williamson has had seven innings against Australia (three in ODIs and four in tests) and averaged 21. Hazlewood has hatched a clear plan which will no doubt continue into the second test in Christchurch.
If there are genuine issues, how Williamson works through them will be fascinating.
Perhaps he has just had a series of good balls, and every batsman goes through fluctuations in their career.
New Zealand batting coach Craig McMillan subscribes to that theory.
"There's nothing major he's doing differently since Australia. He's just not quite nailing those scores like earlier in the season.
"It was just a good piece of cricket that got rid of Kane. It's their best bowler against our best batsman which makes for an intriguing battle."
Few work harder at their game than Williamson, and he is blessed with a self-analysis gene which has a knack for identifying weakness. This will likely be a blip rather than a trough.
The onus now goes on his teammates today, with six wickets in hand, to prove to their likely future skipper they have the mettle to match him, despite batting in the shadow of Australia's gargantuan first innings and the prospect of reverse swing on an increasingly abrasive surface.