Keshav Maharaj remains hopeful South Africa's patience will "pay dividends" after a hard-fought third day of their Test match against the West Indies.

The Windies toiled in the field for 117.4 overs, eventually ending South Africa's first innings just 20 minutes into the opening session as Kagiso Rabada fell on 21 before Lungi Ngidi's four-ball duck.

That same pair of Rabada and Ngidi asked questions of Mikyle Louis and Kraigg Braithwaite with the new ball, yet the Windies openers reached an unbeaten half-century stand with little trouble.

The visiting Proteas turned to Maharaj's spin as early as the 13th over, reaping the rewards as the left-arm spinner ripped through Louis' defence to remove the opener on 35 with the last ball before lunch.

Rain caused a lengthy delay to follow but that stoppage proved fruitful as Wiaan Mulder ran out Braithwaite, on 35, before Maharaj removed Keacy Carty for 42 and Alick Athanaze on just three.

Maharaj bowled 28 straight overs throughout a battling day and hopes South Africa can capitalise with the West Indies on 145-5, some 212 runs behind the visitors' first-innings total of 357.

"When the ball goes in the outfield, it becomes a bit soft and doesn't react much," Maharaj said at stumps. "We have been trying to keep it as dry as possible.

"There is not much off the wicket. I have been trying to use different paces, and various trajectories but only the odd ball is reacting.

"But when you bowl in the right channel for a long time in Test cricket, it does pay dividends."

Kavem Hodge and Jason Holder will hope to provide further resistance when play begins on Saturday in Port of Spain.