Batting first, the South Africans, the highest ranked team in one-day internationals (ODIs), posted a score of 299-6 from their 50 overs at The Oval in London.

That included a score of 103 from Hashim Amla, his 25th century in ODIs.

Faf du Plessis also contributed to the South African total, adding 75 in a second-wicket stand of 145 with Amla.

Du Plessis' edge behind from Sri Lanka's Nuwan Pradeep was the first of four South African wickets to drop for 43 runs.

Following a late resurgence from JP Duminy, who scored 38 off 20 balls, South Africa set Sri Lanka a target of 300 to win in the Group B clash.

They opened their run chase well and were 87-1 after the first 10 overs.

Niroshan Dickwella made 41 from 33 balls before a monumental collapse.

Sri Lanka went on to lose eight wickets for 98 runs, with South African leg-spinner Imran Tahir taking 4-27.

Upul Tharanga, captaining Sri Lanka in place of the injured Angelo Mathews, scored 57 but his removal seemingly brought the game to a close as they were bowled out for 203.

"It was possible for them to chase it down, but we needed a few early wickets, which we got," said South African captain AB de Villiers.

"It was important to assess in the first 10 to 15 overs.

"They bowled exceptionally well, and credit to our openers for seeing it out.

"It's scary, the amount of runs Hashim has piled on in his short career, hopefully [there are] many more to come.

"It was a difficult situation [when to introduce Tahir], it was just a feeling I got, there was no set plan.

"A little breeze, I had a little chat with him, and I just had a good feeling, when I brought him on."

South Africa’s next game is against Pakistan on June 7 while Sri Lanka meet India on June 8.

Tomorrow’s action sees the highly anticipated Group B match between India and Pakistan at Edgbaston in Birmingham.

More than half a billion people are expected to watch the match while tickets for the fixture sold out in ten minutes.