David Miller had garnered the reputation of being an all out blasting batsman, whose primary concern was to put as many deliveries as he could into the crowd.

On Sunday, he demonstrated how far he has come with a composed and mature performance with JP Duminy that rescued South Africa from a potentially embarrassing loss to Zimbabwe in their World Cup opener at Seddon Park in Hamilton.

Miller smashed 138 not out from 92 balls in his world record fifth-wicket partnership of 256 runs with Duminy, who added 115 from 100 balls, as the pair rebuilt South Africa's innings from a precarious 83 for four in the 21st over.

"It was a great knock from JP and David," South Africa captain AB de Villiers said after the 62-run victory. "Great partnership, great knock, they won us the game."

It seems incongruous that about a month ago, there was a suggestion that Miller may not be the right man for the World Cup.

He was reportedly in a battle with Rilee Rossouw for the middle-order batting spot, with concerns that while he could certainly hit the ball very hard and very far, he could not consolidate and build an innings.

Until last month's series against West Indies.

The 25-year-old was patient when he needed to be, building into an innings, rotating the strike to keep the scoreboard ticking over, then unleashing in the final few overs.

He scored 70 and 130 not out, his first one-day international century, and cemented his spot in South Africa's lineup.

All of those characteristics were evident again on Sunday when he combined with Duminy to guide the Proteas to 339 for four.

"It was just about constructing a partnership with someone and JP was the man," Miller said after he was named man of the match. "He batted phenomenally well."

Miller's first 50 runs took 53 balls and included just one boundary and two sixes on Sunday before he kicked into gear.

He brought up his maiden World Cup century from 81 balls on the final delivery of the 46th over and then blasted 30 runs in the 48th off Solomon Mire.

"I really enjoyed constructing the innings," Miller said. "I have been working really hard at that part of my game especially against the spinners with just rotating the strike.

"I'm happy with the performance and hopefully that will continue."