South Africa 164 for 2 (du Plessis 63*, Rossouw 45*) beat Bangladesh 160 (Shakib Al Hasan 48, Rabada 6-16) by 8 wickets
Scorecard and ball-by-ball details
Kagiso Rabada stormed his way to the best figures by any bowler on ODI debut - 6 for 16 - and became only the second bowler to take a hat-trick on ODI debut, after Taijul Islam, as South Africa burst Bangladesh's fifty-over bubble following months of success in the format. The hosts looked a shadow of the team that had beat Pakistan and India as they slumped to their lowest total this year and defended valiantly but, ultimately, in vain.
Pace and pinpoint accuracy from Rabada rocked Bangladesh before their most dependable pairing of Shakib Al Hasan and Mushfiqur Rahim formed the only partnership of substance. Neither batsman pushed on, leaving Bangladesh's tail open to another attack from Rabada and well short of a target that would really test South Africa's depth.
The batsmen will forgive Rabada for stealing the spotlight after he assumed the responsibility of a seasoned seamer in his first game. The 20 year-old was tasked with opening the bowling alongside Kyle Abbott after South Africa opted to leave out Morne Morkel, the only member of their premier pace pack who has been included in the one-day squad. Abbott began, and ended, waywardly, and it was up to Rabada to set the tone. And he did against Bangladesh's senior opener, Tamim Iqbal.
Tamim had not scored a run in the first three overs and Rabada made life more uncomfortable for him with a pair of short balls, before he delivered a full, straight delivery, directed at middle and off. Tamim played down the wrong line and was bowled for a 13-ball duck to give Rabada his first international wicket.
Litton Das gifted Rabada a second, when he flicked a delivery angled into the pads to midwicket to set Rabada up for a hat-trick. His milestone delivery was on a good length, quick and into the pads. Mahmudullah, who was making a comeback after missing the India series with a finger injury, was beaten and hit on the pads and Rabada was surrounded by jubilant team-mates.
All that had taken place with Bangladesh only a tenth of the way into their innings, which already felt over for everyone except Shakib. He came out as though his team were 70 for 3, not 17 for 3, and leaned into a cover drive off the first ball he faced.
His partner could not play with the same stature. Soumya Sarkar, whose aggression was on display in the T20s, became too casual. When Sarkar nonchalantly tried to hit Rabada over the inner ring, he chipped it to cover instead to put Bangladesh into further trouble.
Rabada was given one more over in his first spell but he seemed to have run out gas, so Hashim Amla turned elsewhere to keep the heat on. Imran Tahir was introduced in the 11th over almost had an immediate impact on the game. Tahir appealed for lbw against Shakib and Amla reviewed. Hawkeye showed the ball going down leg and over the stumps.
Tahir did eventually dismiss Shakib lbw, 14 overs and a lot of hard grind later, but by then Bangladesh's situation had barely changed. Shakib and Mushfiqur sought out singles to build a partnership before Mushfiqur slog swept JP Duminy to long-on and Sabbir Rahman was bowled through the gate by Chris Morris before Shakib's himself left Bangladesh with the score on 120 for 7.
That's when Rabada was given a license to search for a five-for and he found it and more. Mashrafe Mortaza edged to Quinton de Kock, allowing Rabada to leapfrog his former bowling coach, Allan Donald, with the best figures by a South African on debut and then he bowled Jubair Hossain to overtake everyone else on the list.
South Africa then seemed to let Bangladesh go. Abbott went wicketless and frustrated himself trying to change that with a mix of full tosses and short balls, and even Tahir went too full. Nasir Hossain took advantage of the lapses in concentration and finished the innings strongly but Bangladesh would have known they did not have enough.
They may have hoped they did when Amla clipped Mortaza to short fine leg in the sixth over and runs dried up for South Africa at the start, largely thanks to Mustafizur Rahman. The left-armer picked up from where he left off against India and displayed a clever selection of cutters and variation of length but he was mostly a man alone.
Quinton de Kock, with Faf du Plessis to guide him, showed maturity in riding out the tough period, but his eagerness to end things quickly was obvious. He took three boundaries off Mortaza's fourth over to signal his intention to speed things up but his acceleration was shortlived. When he tried to drive Nasir Hossain, he handed a catch to cover, which may have prompted South Africa's circumspection.
Rossouw joined du Plessis and the pair then knuckled down, minimised risk and inched their way to the total, helping the side take a 1-0 lead in the series.
Firdose Moonda is ESPNcricinfo's South Africa correspondent