Despite an improved batting performance compared to the first when they were shot out for 193, the Lankan bowling could not sustain the South African batting that chased down their total of 244-8 to win with 43 balls to spare.
They have successfully chased down totals of 194 and 245 and look a much confident side than they were during the Test series.
Sri Lanka had only themselves to blame for failing to exert pressure on the South African batting when both openers Quinton de Kock and Hashim Amla were let off early in their innings.
Kusal Perera put down a sitter at square leg off Amla when he was on four and Akila Dananjaya made a mess of a catch hit straight to him at midwicket by De Kock with his score on 18. On both occasions the unfortunate bowler was ODI debutant Kasun Rajitha. He later picked up his maiden ODI wicket when he had De Kock caught at mid wicket later in the innings.
The two openers made Sri Lanka pay dearly for the lapses by putting together a stand of 91 off 84 balls that laid the platform for South Africa’s win.
Amla not at his best form scored a run a ball 43 and de Kock hit 13 fours and a six in an aggressive knock of 87 off 78 balls to take the Man of the Match award.
Although Akila Dananjaya picked up three wickets that of Amla, Aiden Markram (3) and Faf du Plessis (49) South Africa paced out their run chase nicely to romp home easy winners.
It seemed that Sri Lanka had not learnt their lessons from the first ODI when they lost Upul Tharanga (9) and Kusal Mendis (0) to Nigidi to be 13-2 in the second over. However Niroshan Dickwella and Kusal Perera saw off the opening pair of bowlers Rabada and Ngidi. But Perera who top scored with 81 in the first ODI fell with his score on 12 failing to time a pull off Phehelukwayo that ended up in mid-on’s hands.
Dickwella and Angelo Mathews set about giving the innings some substance with a stand of 67 off 81 balls but South Africa never allowed Sri Lanka to run away with the run rate which was kept hovering around 4 1/2 an over.
The fact that only Mathews and Dickwella made fifties and the next highest score was 19 tells a tale how the South African bowlers controlled the innings.
Dickwella dealt a painful blow on his right ribs off a delivery from Mulder at 31 carried on after receiving some treatment on the field but later while keeping wickets during the South African innings he was forced to leave the field unable to move his right arm. Kusal Perera took over duties as wicket-keeper.
Dickwella batted aggressively to score 69 off 78 balls (10 fours) – his first half century in 16 innings the last one being scored at the same venue against India in August 2016.
Mathews who came to the wicket at 57-3 played a sheet anchor role to hold the innings together.
Apart from a stand of 42 with Shehan Jayasuriya (18) he could not find anyone to stay with him long enough.
When the innings ended he was unbeaten on 79 scored off 111 balls (6 fours) having passed 3000 ODI runs as captain.Du Plessis used his bowlers judiciously in short spells with Ngidi and Phehelukwayo ending up taking three wickets apiece.
Two Lankan bowlers achieved personal milestones during the South African innings with Kusal Mendis contributing to both of them with catches.
Thisara Perera became the ninth Sri Lankan bowler to take 150th ODI wickets when he dismissed JP Duminy for 32 and Suranga Lakmal captured his 100th ODI wicket with the dismissal of David Miller for 3 to become the 17th Sri Lankan bowler.
He series now moves to Pallekele for the third and fourth ODIs scheduled for August 5 and 8.