New Zealand captain Kane Williamson saluted team-mate Colin de Grandhomme after a tense four-wicket win over South Africa at the Cricket World Cup.

Williamson and De Grandhomme compiled the 91-run match-defining partnership before the latter was dismissed for 60 from 47 balls with victory in sight at Edgbaston.

A six followed by a four from Williamson saw New Zealand home with three balls to spare, and he was predictably named man of the match after reaching 106 not out.

However, Williamson preferred to praise De Grandhomme, whose quickfire runs gave the Black Caps momentum at a crucial stage of the contest.

"Colin de Grandhomme stood out for me today, in terms of with the ball and then the impetus he came and showed with the bat was really special," Williamson said.

"It was a superb knock from him."

Williamson said of his own task with the bat: "It's trying to do the job as well as you can, and I was fortunate I was able to do it today. There were a number of other contributions that were so vital throughout the innings.

"Today was a really close match - could have gone either way - but it was nice to get a win."

New Zealand remain unbeaten and look to be heading to the semi-finals. Williamson's opposite number Faf du Plessis, by contrast, is facing World Cup elimination with South Africa.

Du Plessis said after a fourth defeat of his team's campaign: "Performances haven't been there. Individually we would have liked to have taken on more responsibility to put on performances that could drive the team home but it hasn't been there.

"But we are fighting as a team and I think you saw that today."