Quinton de Kock led a resolute effort as South Africa lost just one wicket in advancing to 205 for five, a lead of 108 runs, at lunch on the second day of the first Test against the West Indies in St Lucia on Friday.
Having struggled in his previous four Test matches with the burden of captaincy, De Kock seemed more at ease without that responsibility in reaching 44 not out at the interval.
He will resume in the afternoon session with all-rounder Wiaan Mulder (21 not out), the pair having added 43 runs so far for the sixth wicket in extending their team's lead after the hosts were bowled out for 97 on the first day.
West Indies' only success in the first two hours' play in the day came at the midway point when former captain Jason Holder induced an outside edge from the bat of Rassie van der Dussen and Shai Hope held the catch at gully to end the right-hander's innings at 46.
He had resumed overnight in partnership with de Kock and watched from the non-striker's end as his partner got his team off to an ideal start from the close of play position of 128 for four on day one.
De Kock capitalised on loose bowling at the start of the day from Kemar Roach, the West Indies' senior seamer taken for two boundaries in the opening over to set the tone for the early part of the morning when more boundaries flowed off the bats of both batsmen.
Jayden Seales, the 19-year-old debutant fast bowler who impressed with three wickets on the first day, battled to keep the runs in check but it took the introduction of Holder to bring the much-needed breakthrough.
However South Africa's determination to build a potentially match-winning first-innings advantage has not been significantly dented by that setback, with Mulder playing with calm assurance in support of de Kock.
An additional consideration for the West Indies is to readjust their batting line-up to accommodate opener Kieran Powell, who has come into the XI as a concussion replacement for Nkrumah Bonner, who was struck flush on the helmet by Anrich Nortje off the first ball he faced in his innings on the opening day.