Big picture
It was only three months ago that Sri Lanka travelled the length and breadth of South Africa, only to be walloped 5-0 in the ODIs and 3-0 in the T20Is. Their bowlers were flayed all around while the batsman were repeatedly tormented by a fiery attack. Lasith Malinga struggled for impact and looked spent, grumpily berating his team-mates' attitude. What a different three months can make.
Malinga might still be the World Cup's grumpiest uncle, but he's also fired his team up to keep them still very much in contention for a semi-final spot. The South African camp, meanwhile, have their pride (and jobs) on the line after five defeats in seven games. South Africa's failure has been as incomprehensible as Sri Lanka's success, but here we are.
For South Africa, this match - and their final game against Australia - will present an opportunity to bid farewell, at least in this format, to Hashim Amla, JP Duminy and Imran Tahir, who are all set to retire from ODIs after the World Cup. For the moment, they are a team in limbo, with one foot in the past even as they eye the future.
Sri Lanka aren't quite done with the business of this World Cup, and their focus is very much in the present. Their victory over England and England's subsequent defeat to Australia have opened up the qualification race, and Sri Lanka could still reach 12 points if they win all three of their remaining games, potentially with a little wriggle room in the top four. They may well need it, if their mercurial run through this tournament so far is anything to go by.
Their two victories have been counterbalanced by two massive defeats - by 10 wickets and 87 runs - and the weather has also followed them around, with two of their matches rained off. The weather shouldn't be an issue this time around, and against a team who are out of contention and deep in introspection, Sri Lanka's biggest challenge could be to overcome their own inconsistencies.
Form guide
South Africa: LLWLL (Last five completed matches, most recent first)
Sri Lanka: WLWLW
In the spotlight
Rassie van der Dussen is possibly the only South African who will leave this World Cup with his reputation enhanced. Van der Dussen has not scored enough runs to outweigh South Africa's general inadequacies with the bat, but two fifties and an average of 54 in his very first World Cup campaign are not to be sniffed at. He has made a start in every innings, with scores of 50, 41, 22, 67* and 36, and looked to be proactive when set, hitting more sixes (6) than anyone else in his team so far. As South Africa look to move forward after the World Cup, it's possible that van der Dussen could be asked to play a crucial role - possibly even as a captain, with the incumbent Faf du Plessis suggesting he has "massive leadership potential".
How much does Lasith Malinga have left in the tank? He turned back the clock with the four biggest wickets in England's top order to help set up a 20-run win in Sri Lanka's last outing, and in the last two years he has been Sri Lanka's go-to bowler in every phase of the innings. When Malinga does well, Sri Lanka tend to also, and they need more of the same in their last two group games.
Team news
South Africa's selections are somewhat academic at this point, but they may look to give JP Duminy an outing ahead of what could be the final ODI of his career against Australia.
South Africa: 1 Quinton de Kock (wk), 2 Hashim Amla, 3 Aiden Markram/JP Duminy, 4 Faf du Plessis (capt), 5 Rassie van der Dussen, 6 David Miller, 7 Andile Phehlukwayo, 8 Chris Morris, 9 Kagiso Rabada, 10 Lungi Ngidi, 11 Imran Tahir
Nuwan Pradeep is down with fever and could miss out. Suranga Lakmal is likely to come in.
Sri Lanka: 1 Dimuth Karunaratne (capt), 2 Kusal Perera (wk), 3 Avishka Fernando, 4 Kusal Mendis, 5 Angelo Mathews, 6 Jeevan Mendis, 7 Dhananjaya de Silva, 8 Thisara Perera, 9 Isuru Udana, 10 Lasith Malinga, 11 Suranga Lakmal
Pitch and conditions
This is Chester-le-Street's first match of the World Cup, and a fresh pitch could well encourage the bowlers early on. The average first innings score at this ground in the last five ODIs played here is a modest 262, and the team that bowls first has won three of those games and nine times out of 16 overall. Fortunately, the weather is expected to be fine on Friday.
Strategy punt
Dhananjaya de Silva's offspin could form the basis of a solid game plan against Quinton de Kock, who walloped three half-centuries and a hundred in the ODI series against Sri Lanka in March. De Kock hasn't exactly struggled against Dhananjaya in the past, averaging 40.5 against him, but has been out to him twice. On his part, three of the five wickets Dhananjaya has picked at this World Cup have been left-handers. Almost a quarter of de Kock's dismissals in ODIs have been to offspinners, against whom he averages 38.4 (compared to a career average of 45.23). Against him, Dhananjaya could be Sri Lanka's secret weapon.
Lungi Ngidi is yet to take a wicket in the Powerplay this World Cup, and has conceded runs at 7.2 an over at the top of the innings. Should South Africa consider using him as a first change bowler? While he has been ineffective with the new ball, Ngidi has taken all seven of his wickets at the death, and his economy rate of 6.4 in the last 10 overs is one of the best in the tournament. If South Africa allow Chris Morris, who has an economy of just 3.3 in the first 10 during this tournament, to partner Kagiso Rabada with the new ball, Ngidi could be given an extended spell at the back end of the innings.
Stats and trivia
Sri Lanka have never lost an ODI at the Riverside Ground, having played here twice. This will be South Africa's first game in Durham
Ngidi has taken 18 wickets in 9 innings against Sri Lanka at an average of 18.8, his best against any top 10 ranked opposition in ODIs
Quotes
"What's left to play for is really ourselves. We've dedicated the last two years to coming here and winning the tournament. We can't let two weeks' work reflect badly on us."
South Africa's assistant coach Malibongwe Maketa
"We think that we have a good chance because we are coming off two wins and a very good win against England, although we didn't play our best cricket to win the game in terms of batting. I think we had a perfect bowling display, defending that target."
Sri Lanka coach Chandika Hathurusingha