A maiden international century by Heinrich Klaasen set up a 74-run win for South Africa in the first one-day international against Australia at Boland Park on Saturday.

Klaasen hit 123 not out in a South African total of 291 for seven. Australia were on target midway through their reply but lost their last seven wickets for 43 runs to be bowled out for 217.

Steve Smith and Marnus Labuschagne put on 84 for Australia's third wicket after the early loss of opening batsman Aaron Finch and David Warner, both dismissed by Lungi Ngidi, who finished with three for 30.

Smith (76) and Labuschagne (41) hit only three boundaries between them as scoring proved difficult on a slow pitch and a big outfield.

When they tried to accelerate Labuschagne was caught at long-on off left-arm spinner Keshav Maharaj.

Mitchell Marsh helped Smith add 41 for the fourth wicket but Marsh was bowled by Ngidi and three balls later Smith was trapped leg before wicket by Anrich Nortje.

It was always going to be difficult for new batsmen to get established and the innings subsided.

By contrast Klaasen and David Miller (64) put on 149 for South Africa's fifth wicket and were not parted until Miller was out in the 49th over.

"That was the difference between the teams," said Australian captain Finch. "Klaasen and Miller batted really well. When you have a couple of batters going deep – they scored something like 81 runs in the last ten overs." It was actually 82 but it proved crucial.

Klaasen said he felt "pure emotion" when he reached his century after a difficult recent period when he lost his place in the team and had to fight his way back. He gave credit to Miller and new cap Kyle Verreynne, who made 48 and helped Klaasen add 78 for the fourth wicket after South Africa had been 48 for three after winning the toss.

Verreynne, 22, made an impressive debut which included three catches in the outfield by a player who keeps wicket in domestic cricket. Two of Verreynne's catches were spectacular, one to dismiss Warner when he dived forward from point and late in the innings when he ran in from long-on and dived to take a steepling catch from Pat Cummins.

South African captain Quinton de Kock was phlegmatic after a topsy-turvy few weeks when South Africa have had good wins interspersed by heavy defeats. "It's a matter of being consistent in what we do and then we will be alright going forward," he said.

The three-match series continues in Bloemfontein on Wednesday.