Pollock top-scored 54 off 40 balls and took one for five in three overs as the Ntini XI won by five runs on the Duckworth/Lewis method. He also contributed a direct-hit run-out.
The invitation team scored 176 for nine in the 25-overs-a-side match to mark the benefit season of South African fast bowler Ntini. The West Indians were 110 for five after 16.2 overs when rain brought the match to an early end.
Pollock will lead South Africa in a Twenty20 international in Port Elizabeth Sunday, with regular captain Graeme Smith ruled out because of a virus.
The Ntini XI were struggling at 106 for seven before Pollock and Ntini shared a 52-run stand for the eighth wicket. Pollock hit two fours and three sixes before he was caught in the deep.
Jacques Kallis looked in good form, hitting two sixes in an over off left-arm opening bowler Pedro Collins before being caught behind off stand-in captain Dwayne Bravo for 27 off 20 balls.
Jonty Rhodes, who retired from top-level cricket after being injured during the 2003 World Cup but has remained involved as fielding coach of the South African team, made 25 off 23 balls. His innings included a trademark pulled six off Darren Sammy.
Pollock plunged the tourists into early trouble when Brenton Parchment was leg before and Devon Smith was run out after a smart piece of fielding by Pollock off his own bowling.
Shivnarine Chanderpaul struck a confident 44 off 27 balls for the West Indians but he was caught and bowled off a leading edge by former South African left-arm spinner Paul Adams in a crucial blow shortly before the rain came down.
Bravo said he was disappointed that rain had stopped the match but was pleased that his players had shown an aggressive attitude, even though it was a benefit match. "We tried to be as competitive as possible and to build on our series win in Zimbabwe with some big games coming up," he said.