Kumar Sangakkara top-scored with 74 not out as Sri Lanka cruised to a seven-wicket win over struggling South Africa in the fourth one-day international in Dambulla on Saturday.

South Africa's defeat, against a team resting four players, left them trailing 4-0 in the five-match series and extended their losing run to nine successive matches.

Sri Lanka, set a competitive 236-run target after a fine unbeaten 52 from Shaun Pollock, recovered from a slow start to win with 23 balls to spare thanks to fifties from Avishka Gunawardene and Sangakkara.

The hosts had started their run chase badly when opener Sanath Jayasuriya was run out after a mix-up with Gunawardene in the fifth over.

But Gunawardene, who survived two difficult slip chances on 13 and 32, fought back to score 52 from 64 balls, hitting seven boundaries.

The left-hander added 59 in 79 balls with Saman Jayantha, who had been called up to gain match practice before next month's Champions Trophy in England.

Straight after the first drinks break, Gunawardene nicked a catch behind off Makhaya Ntini to leave Sri Lanka 72 for two, but Jayantha shared a 65-run stand with Sangakkara.

After a slow and nervous start, during which he was dropped by wicketkeeper Mark Boucher on 12 and fortunate not to be adjudged leg before wicket on 15, Jayantha scored 46 from 73 balls and swept one massive six.

Jayantha eventually skied a catch into the deep, but Sri Lanka never surrendered control of the game as Sangakkara shared an unbroken 98-run stand from 90 balls with Mahela Jayawardene (48 not out).

Earlier, South Africa captain Graeme Smith led from the front with 46 from 64 balls, sharing a 47-partnership for the first wicket with Herschelle Gibbs (27).

Smith then added 52 in 65 balls with Jacques Rudolph (24) to leave the tourists in a strong position on 113 for two in the 22nd over.

But a mid-innings wobble, during which three wickets tumbled for two runs, left the South Africans in trouble on 115 for five.

Rudolph was run out by Farveez Maharoof, then leg spinner Kaushal Lokuarachchi trapped Smith and Jean-Paul Duminy leg before wicket in his third over.

Pollock resuscitated the innings in a 64-run stand with Mark Boucher (27) and guided South Africa to a competitive total with a late surge as 49 runs were plundered from the last five overs.

Sri Lanka used eight bowlers with leg spinner Lokuarachchi the pick of them, finishing with two for 39.

Scoreboard:

South Africa innings
G.Smith lbw Lokuarachchi 46
H.Gibbs b Fernando 27
J.Kallis b Maharoof 7
J.Rudolph run out 24
M.Boucher b Chandana 27
J-P.Duminy lbw Lokuarachchi 0
S.Pollock not out 52
L.Klusener st Sangakkara b Dilshan 12
N.Boje not out 19

Extras (lb-3 nb-4 w-14) 21

Total (for seven wickets, 50 overs) 235

Did not bat: R.Peterson, M.Ntini

Fall of wickets: 1-47, 2-61, 3-113, 4-115, 5-115, 6-179, 7-195.

Bowling: Malinga 5-0-40-0 (4nb), Fernando 5-0-28-1 (3w), Maharoof 6-0-20-1 (2w), Dilshan 6-0-44-1 (1w), Jayantha 1-0-7-0, Jayasuriya 10-2-24-0 (1w), Lokuarachchi 10-0-39-2 (2w), Chandana 7-0-30-1 (5w)

Sri Lanka innings
A.Gunawardene c Boucher b Ntini 52
S.Jayasuriya run out 8
S.Jayantha c Duminy b Peterson 46
K.Sangakkara not out 74
M.Jayawardene not out 48

Extras (lb-4 nb-1 w-3) 8

Total (for three wickets, 46.1 overs) 236

Did not bat: T.Dilshan, U.Chandana, F.Maharoof, K.Lokuarachchi, L.Malinga, D.Fernando

Fall of wickets: 1-14, 2-73, 3-138

Bowling: Pollock 7.1-1-24-0 (1nb), Kallis 9-0-49-0 (1w), Klusener 6-0-38-0 (1w), Ntini 8-0-39-1, Boje 8-0-36-0, Peterson 3-0-22-1, Duminy 5-0-24-0 (1w)

Result: Sri Lanka won by seven wickets to lead the five-match series 4-0.

Final match: August 31, Colombo