West Indies have romped through South Africa's top and middle order on a rain-affected third day of the second Test to leave the tourists tottering at 6-63 in their second innings at tea.
South Africa still lead by 212 runs, but the West Indies gave themselves a fighting chance in the final Test on Sunday as they look to rescue a draw in the series.
Medium pacer Kyle Mayers was key with 3-14 as the West Indies snatched five wickets for 21 runs amid the South African collapse.
Only 24 overs of play were possible before tea because of the weather. Rain wiped out the whole of the first session on day three in St Lucia and returned in the afternoon to force an early end to the second session.
Despite the delays, there was still enough time for the West Indies to have a dramatic effect on the match.
South Africa No. 3 Rassie van der Dussen was 22 not out and the only recognised batsman surviving for the Proteas, who had hopes of driving home an unassailable lead in their second innings.
West Indies made inroads straight away when Kemar Roach removed Aiden Markram to an edge to the slips in the first over of the innings. Roach also sent South Africa captain Dean Elgar back for 10.
Mayers' introduction saw South Africa slip further as he dismissed Keegan Petersen (18), Kyle Verreynne (6) and Wiaan Mulder (0) in quick succession.
Jason Holder snatched the crucial wicket of the in-form Quinton de Kock and the West Indies players whooped with delight when the danger man edged to wicketkeeper Joshua Da Silva for a duck.
De Kock had made 141 not out and 96 in his two other innings this series.
South Africa won the first Test, also in St Lucia, by an innings and 63 runs and were also seemingly in command of the second game after making 298 in their first innings and bowling West Indies out for 149 for a lead of 149.
Australian Associated Press
