Sri Lanka overwhelmed South Africa by 128 runs in the fifth and final one-day international on Wednesday to complete a 4-1 series defeat.
It was the worst one-day series performance by the Proteas since losing to 4-0 to England in 2008.
Half-centuries from Tillakaratne Dilshan (99), Lahiru Thirimanne (68) and Kumar Sangakkara (75 not out) took Sri Lanka to an imposing 307 for four after they had won the toss and elected to bat.
South Africa were then all at sea against the Sri Lankan spinners and slumped to a disappointing 179 from 43.5 overs.
Captain AB de Villiers top-scored with a run-a-ball 51 but the other batsmen failed to come to terms with the slow turning pitch.
Ajantha Mendis was again the main tormentor of the South African batsmen picking up three wickets for 36.
He was well supported by fellow spinners Sachitra Senanayake (2-29) and Dilshan (1-41).
Fast bowler Suranga Lakmal, who replaced Lasith Malinga for this game, took a career best three for 22.
Dilshan and Thirimanne set up the Sri Lankan innings with a second wicket stand of 163 which provided the ideal platform for Sangakkara to attack the tiring South African bowlers who wilted under energy-sapping hot and humid conditions.
Man-of-the-match for the second consecutive time, Dilshan missed out on his 18th one-day hundred by one run when he was bowled by Ryan McLaren for 99 scored off 110 balls with 12 fours.
Thirimanne, promoted to number three, stuck it out for 93 balls to score 68 with one six and six fours.
Sangakkara, who batted at number four, was soon hitting the ball serenely to all parts of the ground.
His innovative innings came off 45 balls with 12 fours and took his aggregate in the series to 372 runs, the highest scored by a Sri Lanka batsman in a bi-lateral series.
With 13 dismissals behind the stumps, Sangakkara was the clear choice as man-of-the-series.
Sangakkara also became the leading run scorer in one-day internationals for the current year, taking his aggregate for 2013 to 883 runs from 17 matches to overtake Pakistan captain Misbah-ul-Haq's of 808 from 18 matches.
The teams meet in the first of three Twenty20 internationals in Colombo on Friday.