New Zealand captain Kane Williamson hailed record-breaking Virat Kohli as "the best" batsman in the world and warned India's rivals that the superstar is "getting better."

India, who Williamson described as a "blue machine", defeated his side by 70 runs in Mumbai on Wednesday to reach the World Cup final.

India piled up 397-4 with Kohli hitting a record-setting 50th one-day international hundred before being dismissed for 117 and Shreyas Iyer making 105.

Mohammed Shami then took a sensational 7-57 under the Wankhede Stadium floodlights as New Zealand, the losing finalists at the last two World Cups, and 2019 semi-final conquerors of India, were bowled out for 327.

A world-class batsman in his own right, Williamson paid tribute to Kohli, who surpassed the record of 49 ODI hundreds he had shared with Sachin Tendulkar as the retired India great looked on from the stands at his old home ground.

"That's something quite special, I think if you play 50 games, some people would call that a great career," said Williamson.

"But to get 50 hundreds...and not just that, actually the way he goes about it, it's actually about winning games for his team."

The 33-year-old added: "I mean he's the best, isn't he? And he seems to be getting better, which is a worry for the opposition all around the world."

Shami struck throughout the innings on his way to returning the best figures by any bowler in a World Cup semi-final and, importantly ended a threatening third-wicket stand of 181 between Daryl Mitchell (134) and Williamson (69) when the Black Caps skipper was caught at deep square leg.

"That blue machine keeps rolling and they were too good for us today...They thoroughly deserve their win," said Williamson.

Shami's return took him to the top of the tournament bowling charts with 23 wickets even though the paceman missed the first four games before an injury to all-rounder Hardik Pandya led to a recall.

"He (Shami) has been incredible," said Williamson. "He's coming on first change, behind two outstanding new ball bowlers (Jasprit Bumrah and Mohammed Siraj).

"He's without a doubt one of the top operators in the world and the way he moves the ball and he keeps bringing the stumps into play.

"It's been quite phenomenal really, the amount of wickets he's gotten in such a small amount of games in this tournament."

Mitchell's hundred was his second of the tournament after he made 130 against the impressive India attack in a four-wicket pool defeat in Dharamsala.

"He's a phenomenal player and just the ultimate competitor, he loves the occasion, and he's been outstanding for us throughout this whole tournament," said Williamson.

India, unbeaten in 10 games at the tournament, will now face either Australia or South Africa in Sunday's final in Ahmedabad.

"They're the best team in the world and they're all playing their best cricket," said Williamson.

He added: "The way they've played throughout this tournament has been incredible. They haven't missed a beat...I've got no doubt they'll go into that next match full of confidence."