With an eye operation pending, Ross Taylor wondered whether he would even play the second Test match in Hamilton.
But a gutsy 102 not out has proved crucial in giving his side the upper hand against Pakistan going into the fifth day in Hamilton.
A win or draw will mean New Zealand’s first series victory over their rivals in more than three decades.
The Kiwis declared at 5-313 late on Monday, giving Pakistan a victory target of 369.
Their openers Azhar Ali and Sami Aslam will start the final day with one run on the board after surviving the final three overs.
The highest successful fourth innings chase at Seddon Park was Australia’s 4-212 in 2000.
Before the match the 32-year-old Taylor revealed the problems he has had with a pterygium, or a growth, on his left eye.
After the match he will have surgery to get it cut out and he'll miss the Chappell-Hadlee one-day series against Australia.
During his 102, his 16th Test century, he was struck on the gloves more than once and revealed his hands were bleeding when he took them off at the end of the day.
He also admitted that since the first Test in Christchurch, won by eight wickets, he'd been wondering if he would even play in Hamilton.
“Obviously I’m very happy I made that decision,” he said.
If Pakistan win they will retain their second spot on the ICC Test ranking table, a draw or a loss will lower them to fourth.
If New Zealand win they will rise one spot to sixth.
Pakistan left-armer Mohammad Amir says they will be going out to win the match on the last day.
Pakistan haven’t lost a series since 2014.
“It’s very important to us. We like to be among the top teams of the world and we try our best to retain it,” Amir said.
After winning the toss and asking New Zealand to bat on a Seddon Park green top, Amir conceded they'd allowed the hosts to score too much in the first innings.
New Zealand rattled up 271 and then dismissed Pakistan for 216 over three rain-interrupted days.
On Monday, their 5-313 was built around Taylor’s ton and contributions from Tom Latham (80), Kane Williamson (42) and Colin de Grandhomme (32) on a wicket getting better and better for batting.
Imran Khan picked up 3-76.
