KOLKATA (REUTERS)

It needed something special to end South Africa's unbeaten run in the Twenty20 World Cup ​and New Zealand opener Finn Allen produced exactly that, the fastest hundred in the tournament's history, to propel his team into the final at the Eden Gardens on Wednesday.

South Africa strung together seven wins in a ⁠row to march into the semi-final against a New Zealand side they had blown away ​in a group stage match earlier in the tournament.

The 2024 runners-up had snatched the ​favourite's tag ‌from defending champions India, whom they steamrollered in ⁠a Super ​Eights match underlining their title aspirations.

The odds favoured them but New Zealand lifted their game just when it mattered to book their second appearance in the final of the T20 World Cup.

"It was nice," New Zealand captain Mitch Santner said after they won with 7.1 ‌overs to spare.

"We knew how good South Africa are and they've shown it ‌throughout this tournament. To get a good performance like that against them is pleasing.

"We weren't as good as we could have been in defeat in the group stage. But today was ​about trying to chop and change during bowling because the wicket was good. It was a short ground with a fast outfield."

While Allen set alight the stadium with his sensational power-hitting, the foundation of their nine-wicket victory was laid by their bowlers, who restricted South Africa's fiery batting lineup to a modest 169-8.

Off-spinner Cole McConchie took out ‌left-handers Quinton de Kock and Ryan Rickleton ​in his first over and South Africa, who slumped to 77-5 in the 11th over, could never really recover.

Marco Jansen (55) powered them to a competitive total but the pitch had eased by then.

Allen and Tim Seifert (58) combined in a 117-run opening ​stand that effectively killed off the contest.

Allen ‌smacked ⁠10 fours and eight ‌sixes in an incendiary knock, sealing their victory ‌with a four that also brought up the fastest hundred in a T20 international between two full-member nations.

"To get to 170 was a ⁠great effort and we felt we had a sniff," South Africa captain Aiden Markram said.

"But ​as it goes in T20 cricket, the powerplay got off to a flyer and it was hard to pull back. You give credit to their openers to kill the game like they did. A bad night for us tonight.

"It feels like a slap in the face and we need to be better as a team."

Defending champions India ​take on twice champions England in the second semi-final in Mumbai on Thursday.