In between the showers, South Africa lost the wicket of Dean Elgar to reach 55 for two wickets before umpires took the players off for an early lunch.
At the interval, Quinton de Kock was unbeaten on 28 with skipper Hashim Amla on four with the tourists needing to survive two more session to avoid defeat and reclaim the number one test ranking with a series victory.
Chasing an unlikely 369 runs for victory, South Africa are more likely to ensure they hold on for a draw than pursue the 314 runs required to sweep the two-match series.
Sri Lanka captured Elgar's wicket from the second ball after the first break for rain when a Dilruwan Perera delivery beat the opening batsman's forward prod to hit off stump.
Elgar lasted 65 balls and shared a partnership of 43 with De Kock before the second, heavier shower forced the players off the field again.
- Sports & Recreation
- Dean Elgar
- Hashim Amla
- Quinton de Kock