Skipper Babar Azam produced a clinical performance with the bat as Pakistan down New Zealand by six wickets Saturday.
After choosing to bat first, the Black Caps appeared to be on course for a modest total at Hagley Oval before Chapman’s 32 off 16 balls, which featured three fours and two sixes.
Pakistan can go clear in the series if they can chase down their target, having beaten Bangladesh by 21 runs in the series-opener at the same venue on Friday.
The three teams are using the week-long tournament to prepare for the T20 World Cup in Australia this month.
New Zealand laid the foundation of their innings through opener Devon Conway (36 off 35) and captain Kane Williamson (31 off 30), although both struggled for timing during a 61-run stand for the second wicket.
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It was another frustrating outcome for the accomplished Williamson, who has passed 50 on just two occasions in all formats over the last 18 months, a period that has encompassed 29 innings.
He was clean-bowled attempting a slog-sweep off spinner Mohammad Nawaz, while Chapman holed out to a slower ball from Pakistan’s best bowler, paceman Haris Rauf (3-28).