Aiden Markram and Kyle Verreynne hit half-centuries Friday in the South Africa second innings to help give the Proteas a 239-run lead after the second day of the second cricket test in Guyana.
At stumps, South Africa was 223-5 after scoring 160 in its first innings Thursday. The West Indies side was all out for 144 in its first innings earlier Friday.
Markram scored 50 and Verreynne was unbeaten on 51. Jason Holder (54 not out) and Shamar Joseph (25) shared a 40-run, 10th-wicket stand to move the home side to within 16 runs of the South Africa first-innings total.
Eight wickets fell on the second day at Providence Stadium after 17 on the opening day. Wiaan Mulder took four wickets for South Africa and Jayden Seales was 3-52 for the West Indies so far in the South Africa second innings after also taking three in the first.
The teams played to a rain-affected draw in the first test in Trinidad. The two-test series will be followed by three Twenty20 matches.