Sri Lanka 236 for 3 (Sangakkara 74*) beat South Africa 235 for 7 (Pollock 52*)
Scorecard and ball-by-ball details
Sri Lanka's dream run continued in Dambulla with an emphatic display that oozed confidence. Despite making wholesale changes and resting four key players, including their captain, Marvan Atapattu, who scored a matchwinning 97 not out in the third match, they cantered past South Africa's 235-run total with nearly four overs and seven wickets to spare, thanks to a controlled and stylish unbeaten 74 from Kumar Sangakkara.
Sri Lanka's run-chase started well with Sanath Jayasuriya teeing off with a cover-drive and a sweetly timed leg-side clip to the boundary after surviving a good lbw shout. But a mix-up while running between the wickets pushed them onto the back foot, as Jayasuriya, responding late to a hesitant call for a quick single to mid-off, was run out by two yards (14 for 1).
Thereafter, Shaun Pollock and Jacques Kallis, who took the new ball in place of the discarded Alan Dawson, kept things tight as Avishka Gunawardene and Saman Jayantha, Atapattu's nervous replacement, played and missed frequently, and struggled to dispatch the bad ball.
Fortunately for Sri Lanka, South Africa were having another bad catching day. Gunawardene, on 13 and 32, was missed twice at slip by Jacques Kallis. Both chances were difficult: the first was a low diving effort and the second, off a full-blown square-cut, whizzed to his right.
After 10 overs, Sri Lanka were 36 for 1, but, gradually, Gunawardene started to settle and find the boundary with meaty tonks over mid-on and forcing strokes through the off side. He reached his 11th one-day international fifty from 61 balls, and when drinks arrived, Sri Lanka were on target on 73 for 1.
But, first ball after the break, Gunawardene wafted at a delivery from Makhaya Ntini and feathered a catch to Mark Boucher - his 250th in one-dayers. He could have had victim No. 251 too, but was unable to hold on to a thin nick off Jayantha in Nicky Boje's first over. Boje's bad luck continued in his second over when Jayantha was perilously close to being out lbw.
But after the let-offs, Jayantha started to relax. He had laboured for 48 balls before hitting his first boundary, but now began to strike the ball more freely. When he bent down on one knee and swept a massive six over midwicket, he was rubbing salt in Boje's wounds.
Sangakkara had fewer qualms, and settled quickly into his stride, keeping things simple and rotating the strike without fuss. South Africa were fast losing control of the game as 65 runs were milked from 85 balls. By the time Jayantha skied a catch into the deep, having made 46 from 73 balls, Sri Lanka were trotting home comfortably (138 for 3).
Mahela Jayawardene, Sri Lanka's stand-in captain, and Sangakkara finished off the job clinically with an unbroken 98-run stand from just 90 balls. Jayawardene ended up on 48 not out from 45 balls.
Earlier, Sri Lanka's decision to field first with a new-look pace attack had been in danger of backfiring as South Africa galloped out of the blocks. But a mid-innings wobble, when three wickets fell for two runs, pegged the South Africans back. Shaun Pollock then nursed the South Africans back into the game with an intelligent 52 not out.
In the absence of Chaminda Vaas and Nuwan Zoysa, the new ball was entrusted to Lasith Malinga and Dilhara Fernando, who were a touch wayward in their first spells as South Africa started rapidly with Graeme Smith and Herschelle Gibbs adding a run-a-ball 47 for the first wicket. Gibbs had made 27 when, not for the first time in the series, missed a pull and was bowled, the ball just clipping the off bail (47 for 1).
Kallis strode out at No. 3 in his 200th game, as South Africa reverted to a more traditional top order, ending the experiment with pinch-hitters. He pulled a majestic six off Fernando but was then uncorked by a jaffa from Farveez Maharoof that nipped back sharply off the seam and crashed into off stump (61 for 2).
Smith, facing growing pressure but apparently safe as captain until the end of the Champions Trophy, knuckled down with Jacques Ruldolph and scored freely off the part-time spinners. The pair added 52 runs in 65 balls. But just when the South Africans were taking full control, cruising on 113 for 2, Maharoof ran out Rudolph (24) with a swift pick-up and direct hit running in from cover.
Smith, who had scored 46 from 64 balls with four fours, fell two overs later, when he missed a sweep off Kaushal Lokuarachchi, who has been confirmed as Muttiah Muralitharan's replacement for the ICC Champions Trophy. Lokuarachchi needed just two balls to send back Jean-Paul Duminy, who shuffled across his stumps and was trapped plumb in front of the stumps (115 for 5).
Pollock and Boucher scrapped hard and were able to consolidate, adding 64 runs in 104 balls. They threatened a late-innings disintegration similar to Wednesday's game, as Boucher was bowled and Lance Klusener (12) was stumped in the final 10 overs, but Pollock shepherded the team sensibly through till the end, squeezing 49 runs from the final five overs.
The runs appeared crucial at the time, but Sri Lanka had read the pitch well in the morning. It was a beauty and with confidence sky-high, Sri Lanka clicked their 15th win in their last 16 matches. South Africa, meanwhile, have lost their last nine games and travel to Colombo looking forward to the end of a nightmare tour.