The West Indies are 88 for two in their second innings after three days of the final Test against South Africa, trailing the Proteas' first innings of 421 by four runs at Newlands.
The South Africans removed the West Indian openers in Sunday's last session at Newlands to build on AB de Villiers' superb century and take the initiative.
The wickets of Devon Smith and Kraigg Brathwaite mean South Africa are well placed to attack the West Indies batting on the fourth day and set up a second victory in the three-Test series.
They won the first match in Pretoria by an innings and 220 runs but drew with the West Indies in the second Test in Port Elizabeth in a rain-affected game.
A series victory for South Africa will see them retain their ranking as the top Test-playing nation.