South Africa know what they have to do: win every game. You might call that a 'known known'. Then, there are the known unknowns, the things South Africa do not, or cannot know. Would AB de Villiers have made a difference? What if Dale Steyn had never
gone to the IPL?
Afghanistan, meanwhile, are practically unknown. Yes, Rashid Khan is a global phenomenon, and there are members of South Africa's squad who have faced him in franchise T20 leagues. And yes, Afghanistan have made their presence felt at the top for a couple of years now, and clearly belong here. But their meteoric rise has only recently brought them into the same elite orbit as South Africa, and a pair of T20Is, six years apart, are the sum total of these two teams' encounters on the world stage. This will be the first ever ODI. How could South Africa know what to expect?
Afghanistan's first three matches in the tournament will have given them some idea. And vice versa. While their bowlers have created opportunities, neither side's batsmen have clicked. The controversies
around Mohammad Shahzad's exit from Afghanistan's squad, and de Villiers attempt to re-enter
South Africa's haven't helped. The destinies of both teams in this tournament will rest upon the outcome of this basement battle. Lose, and you're all but out. Win, and there's hope.
It is a must-win game for Afghanistan, who will still believe they have what it takes to keep their tournament alive. Their statistical window for qualification might be narrowing with every loss and abandonment, but Afghanistan have nothing if not belief and audacity in the face of daunting challenges.
If they need a little inspiration, they need look no further than the tournament that got them here in the first place. At the World Cup Qualifiers last year, they were virtually written off after losing their first three games to Scotland, Zimbabwe and Hong Kong. "Nothing is impossible," declared Rashid Khan, and they went on to win their next five in a row.
South Africa might need to search a little deeper for a historical precedent for their current predicament, but it's out there. If they beat Afghanistan, they will be in exactly the same position as Pakistan were at the 1992 World Cup, having lost three of their first five games on the field, and one to inclement weather. We know how that story ended.
Afghanistan LLLWL (Last five completed matches, most recent first)
South Africa: LLLWW
in the spotlight
Twenty-one-year-old Hazratullah Zazai burst onto the scene with 162 in a T20I against Ireland and averages over 75 in the shortest format. But he's not hit his stride yet in 11 ODIs, averaging just 22.5. Indeed, Hazratullah seems stuck in T20 mode - he is yet to face 50 balls in an ODI innings, or bat beyond the 20-over mark. In almost half of his ODI innings, he's fallen inside the first five overs - a much more serious concern for an ODI opener than it would be in T20s. He got starts against Sri Lanka and New Zealand, making it into the thirties, but in the midst of a general batting malaise from Afghanistan at the World Cup, his tendency to get in and then get out has heaped pressure on the middle order.
This has been a difficult World Cup for Faf du Plessis. Off the field, he's had to deal with the brouhaha around de Villiers and inspiring his team up even as they lose games and players to injury. But he's not had much success on the field either. Undone early by Jofra Archer's pace against England, his departure for 62 - to the only ball that spun all day - turned the tide of the match against Bangladesh, and he was at the wrong end of a Yuzvendra Chahal double-strike against India. No-one has scored more ODI runs for South Africa than du Plessis since 2017, but his dismissals have come at key moments in this tournament. South Africa need their captain to lead
the team through those moments unscathed.
Given the expected conditions in Cardiff, Mujeeb ur Rahman is unlikely to be recalled, though Dawlat Zadran could be if he is fit. Rashid Khan should have recovered from the blow to the head he suffered during the defeat to New Zealand.
Afghanistan: (possible) 1 Hazratullah Zazai, 2 Noor Ali Zadran, 3 Rahmat Shah, 4 Hashmatullah Shahidi, 5 Gulbadin Naib (capt), 6 Najibullah Zadran, 7 Mohammad Nabi, 8 Ikram Alikhil (wk), 9 Rashid Khan, 10 Aftab Alam/Dawlat Zadran, 11 Hamid Hassan
Lungi Ngidi's fitness is still in doubt, and South Africa are unlikely to risk aggravating his injury by playing him unless he is 100% fit. South Africa will need to decide between including Aiden Markram in their top order or JP Duminy in their middle. Both offer something with the ball, too, and though Markram doesn't have a great record against spin, the threat posed by Mohammad Nabi and Rashid Khan to left-handers could see him in the playing XI ahead of Duminy.
South Africa (possible) 1 Quinton de Kock (wk), 2 Hashim Amla, 3 Aiden Markram, 4 Faf du Plessis (capt), 5 Rassie van der Dussen, 6 David Miller, 7 Andile Phehlukwayo, 8 Chris Morris, 9 Kagiso Rabada, 10 Beuran Hendricks, 11 Imran Tahir
Pitch and conditions
Conditions have varied quite widely in the three games played in Cardiff so far, with Sri Lanka collapsing to 136 all out in the first match played here, while England rocketed to 386 in the last. But those three games were also played during the day, and Saturday's match will be a day-night match. How the ball will behave under lights is another unknown - for both sides. If there's any grass left on the track, pace could dominate - and 54 wickets have fallen to the quicks in the last five games played here. It is unlikely to offer much spin.
There is rain predicted during the day, though the weather should clear later on.
While the conditions are unlikely to encourage spin, as a wristspinner Rashid Khan could still be dangerous, especially against a team who have struggled against legspin, both at this World Cup and historically. South Africa have lost five wickets to legspin in the tournament - the most of any team - and as a group, have averaged 27.4 against legspin since 2018, the second lowest of any team at the World Cup. And so rather than hide Rashid behind the pacers, as they did against Australia when he was brought on in the 14th over, and Sri Lanka
when he came on in the 16th, Afghanistan could look to introduce him early as a strike bowler. Rashid has only bowled three times inside the Powerplay in ODIs, but he has excelled in those rare circumstances, with his best average, economy and strike rate of any phase in the first 20 overs.
Should Aiden Markram open? Hashim Amla's biggest struggle this year has been negotiating the new ball: in more than two thirds of his innings, he's fallen inside the first 10 overs. But when he has survived, he has been more comfortable against spin, averaging 91 against slow bowlers and being dismissed just once by a spinner. Markram, meanwhile, averages 40.8 as an opener, and struggles against spin, against which his average falls to 18.3. South Africa could help both men by swapping their batting positions, allowing Markram to
bat in his preferred position, and Amla to escape the perils of the new ball.
Stats and trivia Here's something that you might not know: Rashid actually has a better record against top 10 teams than he does against Associates. Indeed, since the 2015 World Cup, Rashid has the best average (14.7), best economy (3.6) and second best strike rate (24.3) of any bowler against top 10 ranked teams. Since 2017, Rashid has taken more ODI wickets (101) than Kagiso Rabada (67) Recently, Sophia Gardens has favoured pace over spin, with slow bowlers averaging over 40 in the last five ODIs here and taking a wicket only once every seven or so overs. Over the last four years, spinners have averaged 42.4 at this ground, with a strike rate of 47. Pace bowlers have taken 117 wickets at 30.9 at this venue in the last four years. During the same time period, the average first innings score here is 279 for 9. The average winning first innings score is 341 for 8.
"We had a bad start. That's done now, we have to make sure we put all our energy and focus into the now and what's coming up next."
Faf du Plessis wants his team to keep their focus in the present in a must-win match
"Obviously we lost three games, but we have still a chance. Everyone has nine games, so nobody can say who will be in the top four. "
Gulbadin Naib on Afghanistan's chances
Liam Brickhill is ESPNcricinfo's South Africa correspondent