Aiden Markram (106 off 54 balls) smashed a century off 49 balls to create the record of fastest ton in World Cups, while Quinton de Kock (100) and Rassie van der Dussen (108) crossed triple figures, as the Proteas made 428/5.
A rampant South Africa crushed Sri Lanka by 102 runs here on Saturday to begin their World Cup campaign with a huge win, after setting the record for the highest total by any team in the history of the competition. (Scorecard | Highlights | Full Coverage)
Aiden Markram (106 off 54 balls) smashed a century off 49 balls to create the record of fastest ton in World Cups, while Quinton de Kock (100) and Rassie van der Dussen (108) crossed triple figures, as the Proteas made 428/5.
In reply, Kusal Mendis dazzled at the top with a rapid 76, Charith Asalanka top scored with 79 in the middle-order and Dasun Shanaka found form to hit 68.
But the target was way beyond Sri Lanka, who did well to make 326 in 44.5 overs, keeping South Africa on the park for as long as they could.
In fact, the contest ended with the distinction of featuring most runs scored in a World Cup game -- 754 runs were scored here at the Arun Jaitley Stadium.
After Marco Jansen (2/92) cleaned up Pathum Nissanka (0) in the second over, Mendis unleashed a flurry of spectacular sixes on both sides of the wicket to provide Sri Lanka with the early impetus.
With South African pacers spraying their deliveries on his pads, Mendis dispatched each of them far into the stands to raise a 25-ball fifty.
The senior Sri Lanka batter seemed to be waging a lone battle as Kusal Perera (7) and Sadeera Samarawickrama (23) failed to match their partner in his endeavour.
In the absence of any support from the other end, Mendis fell after a 42-ball blitz that saw him hit eight sixes and four boundaries for his 76 runs.
He tried cutting a delivery from Kagiso Rabada (2/50) too close to the body and was caught behind.
Samarawickrama followed Mendis soon, chipping one towards midwicket with Jansen moving quickly in front to take a clean catch, off Gerald Coetzee (3/68).
Asalanka also took a bit of time to settle in, but to his credit, recovered well to hit four sixes and eight fours to make 79 off 65 balls, as by then, it had become abundantly clear that Sri Lanka were only looking to reduce the margin of defeat.
While Dhananjaya de Silva perished for 11, Sri Lanka captain Dasun Shanaka failed to get a move on for a large part of his innings.
But Shanaka too hit his straps, smoking a six and five fours on the trot off Coetzee to bring up his fifty.
Shanaka's innings ended when Keshav Maharaj (2/62) cleaned him up for 68 off 62 balls (6x4s, 3x6s).
Towards the end, Kasun Rajitha swung his bat to a good effect, getting 33 from 31 balls (4x4s, 1x6s).
In the first half, de Kock (100 off 84 balls; 12x4s, 3x6s), Van der Dussen (108 off 110 balls; 13x4s, 2x6s) and Markram (106 off 54 balls; 14x4s, 3x6s) powered South Africa past the highest World Cup total ever, held by Australia, who had made 417/7 against Afghanistan in the 2015 edition.
After De Kock and Van der Dussen set the platform for a massive score with their second-wicket stand of 204 runs, Markram pulverised Sri Lanka.
All three South African centurions -- De Kock, Van der Dussen and Markram -- also recorded their maiden World Cup hundreds.
A total of 39 fours and eight sixes came collectively from the Proteas trio.
Heinrich Klaasen hit another three fours and a six for his 20-ball 32 and David Miller clobbered three fours and two sixes for his unbeaten 21-ball 39.
Making the most of a favourable pitch against a depleted and erring Sri Lankan bowling line-up, South African batters motored on at a high scoring rate in the middle-overs to wrest control.
An early blow was dealt when Dilshan Madushanka pinned Temba Bavuma (8) in front of the wicket, but that was the only moment of joy for the Sri Lankans.
De Kock and Van der Dussen, who came together a mere 10 balls into the contest, were separated only after putting their team in a commanding position with the fourth highest-ever partnership for any wicket for South Africa in the World Cup.
De Kock, set to retire from ODIs after the tournament, was in his elements in getting a hundred.
On the other hand, Van der Dussen celebrated his 50th ODI with a fifth ton of his career, cracking 13 fours and two sixes in the process.
Markram began with two cracking straight drives for four off Madushanka and brought out every conventional stroke in his book to break the record set by Ireland's Kevin O'Brien (50 balls for 100) in 2011.