Azam's 44-ball 69 and Fakhar Zaman's 33-ball 43 took Pakistan to 178-5 in their 20 overs before Shaheen claimed 4-30 to restrict New Zealand to 169 in 19.2 overs
"We saw something special today from Pakistan," said Williamson whose team have now lost four games in a row after starting the tournament with four wins.
Zaman on Saturday clubbed 11 sixes and eight fours in an undefeated 126 as Pakistan beat New Zealand by 21 runs in a rain-hit match where initially they had been set 402 to win.
Fakhar was the star of the show in the opening 20 overs of the innings, slamming nine sixes en-route to a century off just 63 balls.
Zaman was undefeated on 106 while skipper Babar Azam was 47 not out as Pakistan reached 160-1 in the 22nd over when rain halted play.
The Pakistan opener hit 17 boundaries and six massive sixes during his unbeaten knock of 180 not out as the Asian side successfully chased down New Zealand's healthy total of 336-5 with 10 deliveries to spare
Fakhar Zaman smashed a third consecutive century to guide Pakistan to a seven-wicket victory over New Zealand in the second one-day international on Saturday.
Opener Fakhar Zaman hit a splendid century to anchor Pakistan's five-wicket win against New Zealand in the first one-day international in Rawalpindi on Thursday.
Pakistan batsman Fakhar Zaman has been promoted to the team's 15-player squad for the Twenty20 World Cup while leg spinner Usman Qadir has been moved to the travelling reserves due to an injury, the country's cricket board (PCB) said on Friday.
Opener Fakhar Zaman hit his seventh one-day international century to steer Pakistan to a 16-run victory in the first of a three-match series Tuesday against the Netherlands in Rotterdam.
Fakhar Zaman was once banned from playing cricket in his village and beaten by his brothers because he was simply too good -- but he has returned a hero after his starring role in Pakistan's Champions Trophy win.
Mohammad Amir removed all of India's top three as Pakistan routed their arch-rivals by 180 runs in an astonishing Champions Trophy final at The Oval on Sunday.
