Kumar Sangakkara upstaged fellow centurions Graeme Smith and AB de Villiers as Sri Lanka clinched a tight two-wicket win over South Africa in Sunday's fifth and final ODI at the Wanderers in Johannesburg.

Chasing a competitive target at a ground that has witnessed plenty of humdingers in the past, the tourists ultimately surpassed the Proteas' 312 for four off the penultimate delivery of the match.

While it was tail-enders Sachit Senanayake's six clubbed over midwicket that sealed the result, Sangakkara was the backbone of the pursuit. The 12th century of his ODI career and a first against the Proteas brought into the home side's bench bowling strength into question.

With Dale Steyn and Jacques Kallis rested, Wayne Parnell and Albie Morkel were unable to put in enough consistency to hold their heads up high in the senior stars' absence. Lonwabo Tsotsobe and Morne Morkel, meanwhile, were shoddy in their collective bid to lead the depleted attack.

It was largely plain sailing for Sri Lanka, who triumphed over a 300-plus target for the second time in two games. It was largely plain sailing for them on the back of Upul Tharanga and Tillakaratne Dilshan's 46 and 41 respectively at the top of the knock.

A 50-minute rain delay failed to break their stride, but Man of the Match Sangakkara's departure certainly did. Having reached three figures the ball before, the stalwart left-hander holed out to long-off.

His departure sparked somewhat of a collapse, with three more wickets falling amid Lahiru Thirimanne's refusal to go down without a fight. The middle-order man, drafted into the team after Mahela Jayawardene pulled out injured, orchestrated the highest score of his career with a mature 69.

Robin Peterson, however, struck twice across the first three deliveries of the final over of the match. With Nuwan Kulasekara bowled and Thirimanne caught at short thirdman, the spinner had done a fine job in making up for his expense of the previous match. Senanayake, though, held his nerve to slap the winning runs high and hard over the on-side fence.

Left to rue an off day in the field that saw a slew of missed run-outs, a couple of overthrows and needless duffs in the outfield, de Villiers' side will now focus their attentions on the upcoming tour of New Zealand. Sri Lanka, meanwhile, head Down Under for a tri-series with Australia and India.

Earlier Smith orchestrated an ODI career-saving century, while de Villiers' superb run of form continued with a whirlwind 125 not out as the Proteas amassed what ultimately turned out to be not enough.

Dilshan's choice to bowl first was the right move initially, only for the pitch to flatten out a lot quicker than anticipated to feed the Proteas their highest score of the series.

Under tremendous pressure to show that his half-century in the previous match wasn't merely a flash in the pan amid an otherwise dour run of scores recently, Smith tucked into his first ODI century since 2009. While it wasn't the most fluid of his nine tons, with brute force upstaging deft timing for the most part, it went a long way in answering the veteran left-hander's slew of critics.

De Villiers, meanwhile, graduated to the 12th century of his ODI career. The home captain, dropped in the covers by his opposite number before entering the nervous 90s, reached three figures from a mere 88 balls. Striking 10 boundaries to his former captain's nine, de Villiers equaled Smith's six tally at four apiece.

Their 186-run stand - a third-wicket record against Sri Lanka - ended when Smith lucked out at midwicket. Having evaded the fielder time and time again, Dinesh Chandimal was eventually at hand for a good catch to get rid of Smith, who left the arena to a standing ovation.

Whereas Alviro Petersen and Faf du Plessis' earlier failures had threatened to leave the final score in the 270s, de Villiers made sure to get to 300 and beyond, at times batting on near one leg as cramp set in.

Displaying remarkable anticipation and footwork amid the discomfort, the talented right-hander heaved Thisara Perera over the backward square-leg for back-to-back sixes with stroke play that can only be described as audacious.

Morkel and JP Duminy also looked to fill their boots, making sure that the damage done by a 44-run batting Powerplay continued through the final throws of the innings.

Kulasekara and Senanayake were the pick of the bowlers, with the duo wise in taking pace off the ball as much as possible, while Lasith Malinga and Perera - too fast for their own good - were packed away for plenty of expense.