Mendis (76), Asalanka (79) & Shanaka (68) hit defiant, rapid fifties
But Sri Lanka are eventually bowled out for 326 to lose by 102 runs
South Africa post 428-5 - highest total in World Cup history
Markram smacks century off 49 balls - fastest in Men's World Cups - before falling for 106
Van der Dussen and De Kock also hit sublime centuries
The batters exchange singles, with Shanaka keeping the strike for the next over.
The Sri Lankan captain has 26 from 37 deliveries and was definitely the junior member of the partnership with Asalanka. Now the responsibility lies with him.
Steven Finn
Former England bowler on BBC Test Match Special
Gerald Coetzee has hit the track hard today. A tiny little nick through to the wicketkeeper Heinrich Klaasen - standing in for Quinton de Kock who is sat on the sideline with cramp - and he takes a good catch down by his ankles.
Wellage c Klaasen b Coetzee 0 (SL 233-7)
Wellage goes first ball!
One bright young thing bests another, as Gerald Coetzee draws the edge from the new Sri Lankan batter and Klaasen takes the catch at his shins.
Kasun Rajitha comes out at number nine.
Daniel Norcross
BBC Test Match Special commentator
That probably is curtains for Sri Lanka. A clever piece of bowling from Lungi Ngidi - it was slower, wider and tempted Charith Asalanka to slash at it.
Asalanka c Hendricks (sub) b Ngidi 79 (SL 232-6)
Partnership broken, and is that the match?
Shanaka cuts for four and then takes the single to bring Charith Asalanka on strike. Lungi Ngidi delivers a wide, slower ball and Asalanka throws his bat at it - the balls flies into the air in the covers and sub Reeza Hendricks takes the catch down low.
The partnership ends for 82, in comes Dunith Wellalage.
Pommie Mbangwa
Former Zimbabwe fast bowler on BBC Test Match Special
Who is the batter that holds it together for Sri Lanka? The guy up the order who helps set it up for the hitters in the middle order. England have Joe Root and Dawid Malan while Australia have Marnus Labuschagne. South Africa have Temba Bavuma. It feels like Sri Lanka have their anchors today down at five and six.
Charith Asalanka loves taking on the short ball, and Kagiso Rabada offers up the opportunity.
The Sri Lankan batter pulls for a once-bounce four through square leg before crashing another pull through mid-wicket.
12 runs off the over and the required run rate has just come down a little bit...
Pommie Mbangwa
Former Zimbabwe fast bowler on BBC Test Match Special
This has been a good pitch. Fast and bouncey. If you go for your shots, even when you don't quite get hold of it, the ball can still clear the fence.
Wait a second - were Sri Lanka just setting a platform up to now? Both batters take a six from Jansen, Asalanka sending the ball over mid-on before Shanaka top-edges past fine-leg.
Those two blows have taken Sri Lanka to one short of half-way to their target. And they do say you should look to double your total after 30 overs...
Pommie Mbangwa
Former Zimbabwe fast bowler on BBC Test Match Special
Apart from that innings from Kusal Mendis it's felt like the last rites from Sri Lanka almost from the start. They want to make sure they keep improving as the tournament goes on so will want to take some positives here.
Boundary-less over from Kagiso Rabada, returning to the attack in place of Maharaj.
Shanaka pulls for a single to bring up the Sri Lankan 200 and a 50 partnership for this pair.
Pommie Mbangwa
Former Zimbabwe fast bowler on BBC Test Match Special
I thought he dropped it inside the boundary and then picked it up while he's stood over the boundary rope, but the ball had already touched the sponge.
Charith Asalanka keeps getting lucky on the hook!
He's put down again off the bowling of Jansen, this time by sub Andile Phehlukwayo, his hands seemingly closing before the ball could nestle in them. It then drops to the ground and dribbles onto the boundary sponge for four.
Asalanka then top-edges over the keeper for four more - Jansen must be ticking.
Maharaj rattles through another mid-innings over. Asalanka shifts his second ball for four, turning the ball round his legs.
The required run rate now sits at 10.56 per over, with Sri Lanka currently running at 6.88.
Alex Hartley
Former England bowler on BBC Test Match Special
The fielding has been a little sloppy. Almost like South Africa have been tired from the first innings.
Cheerio Tim, and Charith Asalanka should be departing with you.
The Sri Lankan batter hooks Jansen and Rassie van der Dussen is waiting in the deep. The ball comes in at shin height for the South African fielder, but he misjudges the flight of the ball and it drops just of his hands as he drops to his knees to attempt the catch.
Sri Lanka's middle order content now, it seems, to spend some time in the middle and perhaps bat the full quota of overs rather than attempt to pull off a miraculous chase.
Here's Mike Peter to take you through to the bitter end.
Keshav Maharaj through another over of left-arm spin. Three of singles off it.
Here's how he bagged the wicket of Dhananjaya de Silva from a few moments ago.
Alex Hartley
Former England bowler on BBC Test Match Special
Twelve runs coming from that Ngidi over - he's not having the best of days.
Sri Lanka skipper Dasun Shanaka has struggled to get going here. He's six off 11 balls.
But Charith Asalanka has at least shown a little bit more intent, as he heaves the final ball of Lungi Ngidi into the leg side and into the stands.