Sri Lanka is eyeing a big victory as South Africa, needing 490 to win the second cricket Test, was reduced to 5-139 in its second innings at stumps on the third day Sunday.
Spinners Akila Dananjaya and Rangana Herath took two wickets each to place the hosts within five wickets of a 2-0 series sweep.
Theunis de Bruyn was batting on 45 with Temba Bavuma on 14.
Earlier, Sri Lanka declared its second innings on 5-275, setting South Africa a challenging target.
Dimuth Karunaratne top scored for Sri Lanka with 85 while Angelo Mathews (71) and Danushka Gunathilaka made useful contributions.
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Sri Lanka was bowled out for 338 in its first innings and dismissed South Africa for 124, securing a 214-run lead.
