New Zealand captain Daniel Vettori believes his team's conscious effort to improve in key areas helped them beat Pakistan and level their three-match series at 1-1.

They may have been beaten by 138-runs in the first match on Tuesday but the Black Caps hit back with a clinical performance in the second on Friday to win by 64 runs -- a turnaround which delighted the New Zealand captain.

"I think we wanted to improve on some key areas, made a conscious effort and it's pleasing that we were able to turn around in a couple of days; now we must keep the pressure on Pakistan," said Vettori after the win.

The third and final match will be played here on Monday.

New Zealand rode on a return-to-form century by Brendon McCullum (131) who added 126 for the second wicket with Martin Guptill (62) which built the foundation of an imposing total of 303-8 in 50 overs.

"The partnership between McCullum and Guptill set up the victory for us, enabled us to achieve a 300-plus total and put pressure on Pakistan," said Vettori, who also identified Scott Styris's three wickets in two overs as the turning point.

Pakistan got off to a solid start of 77 between Salman Butt (59) and Khalid Latif (45) and were 124-2 when Styris, bowling for the first time in nearly 13 months, grabbed three wickets off just 10 balls.

"I was trying to get some quick overs," said Vettori of his decision to bowl Styris. "Those turned out to be the most influential overs. Scott came into the game to impress and did at a time when Pakistan were coming hard on us."

Vettori praised his team's fielding.

"If you look at a couple of catches and Guptill's run out of Butt then you realise that these can swing games your way," said Vettori.

Man-of-the-match McCullum said he wanted to prove his worth as opener.

"There was some pressure on me coming into this match," said McCullum, who was relieved of vice-captaincy to improve his batting form. "Vice-captain or not, I am a senior player and wanted to prove my worth as an opener."

McCullum, whose only one-day hundred (166) came against Ireland last year, said scoring his second was a big relief.

"Probably I tried to be too aggressive at times, but this time I found the right tempo," said McCullum.

Pakistan coach Intikhab Alam blamed his team's defeat on poor bowling and fielding.

"We had a bad day," said Alam. "We probably gave away 30-40 extra runs and that made the difference. We must improve our fielding because New Zealand is one of the best fielding sides in the world, on a par with South Africa."

Alam defended his decision to promote Shahid Afridi (no runs) and Kamran Akmal (four) to fourth and fifth in the batting order.

"They were my decisions," admitted Alam. "Both batted well in the first match but didn't click in the second."