"Dealt nothing and bluffing hard, playing poker with the joker and some Uno cards."

That line from the Bloodhound Gang probably applies more to Afghanistan than South Africa, though both came into this match with very few of their World Cup chips left to play with. And while you wouldn't have wanted to bet the house on South Africa coming up with their first W in Cardiff, in the end, they were a pretty safe wager. There are supposed to be no easy beats in this ten-team World Cup but Afghanistan are sporting a few bruises by now.

In a sense, South Africa did partially bluff their way to such a comprehensive margin of victory. There had been some debate about whether they might field an all-pace attack, given the prevailing damp conditions and Cardiff's short straight boundaries - though that all depended on the fitness of Lungi Ngidi, who was bowling off his full run during the warm-ups but not risked, keeping in mind the other four must-win matches South Africa face.

Having won the toss, Faf du Plessis was able to hammer away with the four quicks at his disposal, around a couple of interruptions caused by squally showers. There was a grassy sheen on the pitch, much like on the previous Saturday when England and Bangladesh feasted to the tune of 666 runs, but Afghanistan had reached 33 for 0 when the first delay occurred - resulting in a "slap on the wrists" for the South Africa bowlers.

"There was a lot of chat," Chris Morris said afterwards. "At the first rain break, the bowlers got a bit of a slap on the wrist - you need to be more consistent in what we are doing, we don't need to try too much. The wicket is helping us enough. After that rain break, we came on and we were a lot more consistent, a lot more at the batters and everything in the field just clicked for us. We needed a little bit of a pep from the coach and that was quite good."

While Afghanistan rarely looked like getting away they had at least established something of a foundation. It was after the second, more prolonged break for rain that Faf du Plessis played his trump. Imran Tahir would have been the man to miss out if South Africa had opted for pace but du Plessis had betrayed his hunch 24 hours earlier. "Imran is such a world-class bowler even with the wet ball and on a small field," he said. "He's got all the tricks, especially against a team that hasn't faced him before."

Afghanistan actually had faced Tahir before, during the 2016 World T20. Noor Ali Zadran got out to him on that occasion, too. In Cardiff, Noor seemed the designated driver of the Afghanistan innings, playing himself in, dutifully refraining from excess… until wafting around Tahir's first ball, a perfectly flighted googly that jagged back through a yawning gap to hit middle and off.

Four balls later, Asghar Afghan chipped another wrong'un back to the bowler - Tahir fully deploying those tricks du Plessis had referred to, having only used the variation 21% of the time in the tournament prior to this match. A leaping pluck at midwicket from Aiden Markram and a biff to deep midwicket from Rashid Khan - who briefly manhandled his fellow leggie's figures - and Tahir had run circles around the Afghanistan batting. Almost literally, in the case of his celebrations.

Afghanistan had batted sensibly enough through the first 20 overs (if we were to overlook Hazratullah Zazai's impetuous hook to the only man back on the leg side), but South Africa always appeared in control. The change bowlers, Morris and Andile Phehlukwayo, had joined the dots during tight, five-over spells that saw each concede just 13 runs. After the rain swept in again, Afghanistan's attempts to inject some urgency into their innings saw Hashmatullah Shahidi slash Phehlukwayo's fourth ball after the resumption to slip. Then South Africa went all in on Tahir.

At 69 for 2, ESPNcricinfo's Forecaster had predicted Afghanistan would make 262. Ten balls later, after they had shipped 4 for 1, that had been recalibrated to 137, which turned out to be a more accurate gauge.

After all that has gone wrong for South Africa so far in the tournament, pretty much everything went right here. Morris did drop a difficult chance over his shoulder, giving Zazai an early life, but that was the one noteworthy blemish in the field; Quinton de Kock and Hashim Amla then ensured there would be few nerves on the way to a target adjusted upwards on DLS by a mere one run.

"Very relieved," du Plessis admitted. "Feel a little bit lighter. But I think in all our cricket today was much, much better, much more competitive. We spoke a lot about energy in the field and I think you could really see a big difference in the team.

"Really pleased with the bowlers, I thought once again Andi and Chris were very good through the middle. The two of them are starting to put in consistent performances now and that's very pleasing. Imran as always was special, but especially on a wicket like that, where it's not suited for spinners. To get four wickets like that was an amazing bowling performance."

The other pleasing thing for South Africa was that while in other circumstances they might have had to rely on Kagiso Rabada scything through the most brittle batting line-up on show at this World Cup, on this occasion he was only required to hold up an end. Beuran Hendricks, the man handed the invidious task of replacing Dale Steyn, bowled nicely with the new ball, while Morris and Phehlukwayo were rewarded for some classic English line bowling with five wickets between them.

Du Plessis said before this game that hoping would not do South Africa any good (does that, therefore, make them no-hopers?) With their World Cup involvement on the line, they had to start doing, which is what they achieved with a business-like performance. There will be higher-stakes contests to come, when a little more bluff and nonsense may be required, but two points for the win has at least strengthened their hand.

Alan Gardner is a deputy editor at ESPNcricinfo. @alanroderick