Sri Lanka batsman Angelo Mathews takes a run during the second T20 match between South Africa and Sri Lanka on January 22, 2017 at Wanderers Cricket Ground in Johannesburg. / AFP PHOTO / GIANLUIGI GUERCIA

Sri Lanka batsman Dinesh Chandimal plays a shot during the second T20 match between South Africa and Sri Lanka on January 22, 2017 at Wanderers Cricket Ground in Johannesburg. / AFP PHOTO / GIANLUIGI GUERCIA

Sri Lanka batsman Angelo Mathews takes a run during the second T20 match between South Africa and Sri Lanka on January 22, 2017 at Wanderers Cricket Ground in Johannesburg. / AFP PHOTO / GIANLUIGI GUERCIA

Sri Lanka batsman Dinesh Chandimal plays a shot during the second T20 match between South Africa and Sri Lanka on January 22, 2017 at Wanderers Cricket Ground in Johannesburg. / AFP PHOTO / GIANLUIGI GUERCIA

Lungi Ngidi led South Africa's fightback with early wickets.

Debutant Lakshan Sandakan picked up a four-wicket haul to leave South Africa reeling.

Isuru Udana struck late in the innings to keep South Africa to 113.

Niroshan Dickwella got off to a promising start but he failed to convert it.

Farhaan Behardien came up with a fighting knock as he tried to help South Africa towards a competitive total.

South Africa lost early wickets after opting to bat.

David Miller failed to come up with a sizeable contribution.

Angelo Mathews came up with a calm knock under pressure to take Sri Lanka closer.

Dinesh Chandimal helped Angelo Mathews build a good stand.

South Africa fought back late in the death with quick strikes.

Angelo Mathews held his nerve to take Sri Lanka over the line.