Kane Williamson: New Zealand's 'gem of a player' anchors tense World Cup win

It's the final over. Your team needs eight runs for victory. It's tense. So what do you do?

If you're Kane Williamson, you strike your first six of the match to reach a century and put your side within one run of victory.

The New Zealand captain's sublime 106 from 138 balls in a low scoring game anchored the Black Caps to their tense four-wicket World Cup win over South Africa on Wednesday.

Chasing 242 for victory, Williamson hit a six and a four to reach the target with three balls remaining.

"It's the sort of game that makes you prematurely bald," ex-New Zealand captain Jeremy Coney said on Test Match Special.

"Williamson had to battle and battle, not just the pitch, not just the South African side, he was locked in a battle with himself.

"As he walks off now I'm sure there's a premature peak showing."

The win took New Zealand to the top of the Cricket World Cup table, while all but ending South Africa's semi-final hopes.

Ex-England captain Michael Vaughan: "Eoin Morgan grabbed the headlines for his power-hitting exploits yesterday and rightly so, but this Williamson innings was something else. Under immense pressure he played an old school gem. What a player. What a ton."

Former New Zealand captain Jeremy Coney: "It was mental quality from Kane Williamson today. He didn't look comfortable, couldn't play the shots he likes to play and he was frustrated.

"He had to battle the demons in himself. He trusted his instinct that he could do it and the four down to third man in the penultimate over was crucial. He taught his team a lot today."

South Africa captain Faf du Plessis: "I think Kane showed exactly what to do - he found it tricky to score but he waited for one guy, or a period, where he attacked. We had a lot of stop start."

Ex-England captain Michael Atherton: "Gem of a player, Kane Williamson. Composure and class."

Former South Africa batsman Herschelle Gibbs: "Been asking for 100 from someone from the start. Can't win games with 60s and 50s. Kane Williamson great composure under pressure."

Ex-India batsman VVS Laxman: "What a marvellous innings from Kane Williamson. Fantastic game of cricket and his calmness stood out in taking New Zealand home. Terrific stuff."

The century was Williamson's 12th in ODI cricket and his first at a World Cup.

He is averaging 225.00 at this World Cup, his 225 runs coming in three innings, two of which were unbeaten, and has a strike rate of 72.81.

"I don't really rank innings, but each time you go out and contribute to a winning performance is something that you're always wanting to do," Williamson said.

"It was nice I was able to achieve that today."

South Africa had three opportunities to dismiss Williamson. He was dropped on 22 by spinner Imran Tahir in his follow-through, while David Miller fumbled a run-out opportunity with Williamson on 77.

Williamson also got a faint edge on a Tahir delivery that was caught by keeper Quinton de Kock, but it was given not out and the Proteas did not review.

The defeat leaves South Africa all but out of the World Cup, having lost four and won one of their six games.

A number of international players have signed Kolpak deals in county cricket, which means they are unable to play for South Africa again.

Fast bowler Duanne Olivier, all-rounder Wayne Parnell and Kyle Abbott have all moved on Kolpak deals in recent years.

"You always need your human resources, and South Africa is losing their human resources now," former Zimbabwe Test captain Tatenda Taibu told the Test Match Special podcast.

"A weak first-class system does not produce a great national team. I reckon they'll continue losing players if nothing is done by their cricket board or the International Cricket Council."