Daryl Mitchell hit an unbeaten 53 against some sharp Pakistan fielding and disciplined bowling as New Zealand were held to 152-4 in the first Twenty20 World Cup semi-final in Sydney on Wednesday.

The Black Caps struggled to get on top of the attack in the opening 10 overs, smacking just five boundaries as they crawled to 59-3.

Mitchell and Kane Williamson (46) then accelerated in a 68-run stand before they threw the bat in the final few overs. Shaheen Afridi was the pick of the bowlers with 2-24.

New Zealand, who topped Group 1, are aiming to make the final for the second consecutive time as they target a maiden T20 title.

Like New Zealand, Group 2 runners-up Pakistan are in the semis for a second straight year as they look to add to their 2009 World Cup triumph.

The winner will face either England or India -- who meet in Adelaide on Thursday -- in Sunday's final.

Teams batting first have won five from six games played at the Sydney Cricket Ground this tournament and when Williamson won the toss he had no hesitation in asking Pakistan to bowl.

In an eventful opening over, Finn Allen hit Afridi for four off the first delivery then was given out the next ball lbw.

It was overturned on review because of an inside edge only for Afridi to promptly do the same again and this time it was plumb.

Devon Conway and Williamson steadied the ship but some fine fielding restricted them in the six-over powerplay, where only two fielders are allowed outside the 30-yard circle.

It included the spectacular run out of Conway for 21 by Shadab Khan, who scored a direct hit from mid-off.

They suffered another big blow when danger man Glenn Phillips was caught and bowled by Mohammad Nawaz for six.

Mitchell and Williamson began taking more risks after they passed the 10-over mark with the first six coming in the 13th over -- Williamson's first boundary in 30 balls.

The New Zealand captain was finally undone by an Afridi yorker after a 42-ball knock that yielded only two boundaries before Mitchell and Jimmy Neesham, who scored 16, added 29 runs in the final three overs.