The Black Caps were 99 ahead at lunch on day four, having reached 325 for five in their follow on. England captain Ben Stokes had sent them back in after establishing a 226-run first-innings lead but is now facing the prospect of a potentially tricky chase.
Just how much they will need depends largely on Williamson, who put a poor series behind him to reach 63 not out and become his country’s record Test scorer in the process.
England took two wickets in the first session, one apiece for Ollie Robinson and Stuart Broad, but were showing signs of weariness after a long and taxing stint in the field dating back to the second morning.
Williamson started the day by chalking up the major milestone, pinging James Anderson’s fourth delivery off his toes to overtake Ross Taylor’s 7,683 Test runs. He received a fitting ovation for his efforts, but with the match and series at stake there was plenty still to do.
At the other end Henry Nicholls was having a less secure start, nudging Robinson a yard over short-leg off bat and pad then playing and missing on a handful of occasions as the net tightened.
He lasted 35 minutes before getting too close to one, squirting Robinson to third slip where Harry Brook held on at the third attempt. By then England’s lead had been trimmed from 24 over night to just four.
Once that was cleared, Daryl Mitchell set about building New Zealand’s lead as he took the driving seat from Williamson, scoring 41 of their first 50 runs together. He was particularly ambitious off Anderson, refusing to allow the 40-year-old to settle on a length.
England’s seamers were looking justifiably stiff as the innings ticked past 100 overs, to go with the 53.2 that came before the follow-on was enforced, leaving Jack Leach with a big role to play. The Somerset man looked like he had found the answer when he spun one sweetly past Williamson’s outside edge on 45 and Ben Foakes swooped to splatter the stumps.
It took a long assessment of the slow motion replays before the third umpire decided Williamson’s back foot was just back in the crease, a most marginal call that potentially carried New Zealand’s hopes with it.
Mitchell beat Williamson to 50, despite the latter being on 34 when he arrived at the crease, getting there by smearing Leach over the ropes at long-on. But his aggression got the better of him soon after, hacking Broad off the toe-end and allowing Joe Root enough time to backtrack from slip and settle under the catch.
Tom Blundell weighed in with 19 in 24 balls before the break, as England continued to receive reminders that the game was not yet done.