Opener Vishmi Gunaratne's career-best fifty steered the Sri Lanka women to a seven-wicket triumph in Saturday's second T20I against South Africa at JB Marks Oval in Potchefstroom.
The result leaves the three-match T20I series level at 1-1, with the final T20 scheduled on Wednesday in East London.
The Proteas women were without skipper Laura Wolvaardt, who was ruled out due to illness, with all-rounder Nadine de Klerk standing in as captain.