Fast bowlers Vernon Philander and Morne Morkel shared nine wickets to leave West Indies battling for survival against South Africa in the first test at Centurion on Friday.
Philander recorded figures of 4-29 while Morkel took 3-55 as the West Indies was bowled out for 201 in its first innings, then the pair grabbed another wicket apiece as the visitors followed on.
West Indies reached stumps on day three on 76-2 in its second innings, still trailing South Africa by 275 runs.
The only respite for the West Indies came when Dale Steyn limped off midway through an over at the start of the second innings, and Philander bowled just three overs due to cramp.
South Africa captain Hashim Amla was forced to turn to part-timers Stiaan van Zyl and Dean Elgar as a result, but Steyn returned to the field in the final half hour of the day, suggesting he will be fit to bowl again on the fourth morning.
The West Indies' position at the end of the day was all the more disappointing given that they had begun it in steady fashion, with openers Devon Smith and Kraigg Brathwaite putting on a 72-run stand.
The day's initial breakthrough came in controversial circumstances, with Smith given out caught behind off Philander for 35 despite replays suggesting there was no contact with the bat. There was no doubt about Brathwaite's dismissal for 34 though, as his genuine edge was held by Hashim Amla at slip in Philander's next over.
Marlon Samuels and leon Johnson took West Indies safely through to lunch on 110-2, but Johnson fell for 31 shortly after the interval when he scooped a Kyle Abbott delivery straight to cover.
Samuels and Shivnarine Chanderpaul dug in for the better part of an hour, but Morkel broke a crucial partnership when he forced Samuels to play on for 33.
Brief Scores
South Africa: 552/5d lead West Indies: 201 (Smith 35; Philander 4/29, Morkel 3/55) and 76/2 (Johnson 33 batting; Philander 1/3, Morkel 1/26) by 275 runs.