Aiden Markram smashed a 49-ball hundred, the fastest in the history of the men's 50-overs World Cup, as South Africa's rampaging top order helped them thrash Sri Lanka by 102 runs in their tournament opener on Saturday.

There was some brutal batting at the Arun Jaitley Stadium where three of South Africa's top four batters smashed rapid hundreds to help them rack up a tournament record total of 428-5.

Quinton de Kock struck 100 and Rassie van der Dussen hammered 108 but both were overshadowed by Markram's incendiary 106 off 54 balls.

Markram eclipsed Ireland batter Kevin O'Brien's 50-ball century against England in the 2011 World Cup.

Former champions Sri Lanka were all out for 326 in 44.5 overs after brief fightbacks by Kusal Mendis (76), Charith Asalanka (79) and Dasun Shanaka (68).

South Africa's mammoth score replaced Australia's 417-6 against Afghanistan in 2015 as the highest total in the men's World Cup.

Shanaka elected to field after winning the toss and the 1996 champions did not have to wait long for a breakthrough.

Dilshan Madushanka trapped Temba Bavuma lbw in the second over but Sri Lanka did not get a chance to celebrate another dismissal in the next 29 overs with De Kock and Van der Dussen combining in a rollicking 204-run stand.

De Kock pulled Matheesha Pathirana to reach an 83-ball century, celebrating the milestone by punching the air and letting out a scream.

He attempted another pull off the next ball, only to top-edge to mid-on and depart after a whirlwind knock that included three sixes.

Van der Dussen's nearly run-a-ball knock came to an end when he holed out trying to hit Dunith Wellalage out of the park.

Markram, who clobbered 14 fours and three sixes, then took over and boundaries started flowing.

When Sri Lanka returned to begin their chase, Mendis decided to fight fire with fire and raced to a 25-ball fifty, threatening to snatch Markram's record.

Kagiso Rabada came to his team mate's rescue and dismissed Mendis caught behind after the batter's 42-ball blitz that was studded with eight sixes and four fours.

Asalanka and Shanaka made half-centuries down the order but that only affected the margin of their defeat.