Yaseen Vallie scored 102 as Western Province beat the Boland Rocks by 17 runs at Newlands on Friday.
WP posted 300-8 in their 50 overs, with Jonathan Bird (39), Daniel Smith (39) and Gavin Kaplan (38) all chipping in.
Vallie’s knock came off 109 balls and he struck seven boundaries.
Ferisco Adams picked up 4-54 for the Rocks.
The visitors made a good fist of the run chase but were bowled out with eight balls still remaining.
Stiaan van Zyl top-scored for the Rocks with 66, while Michael Copeland made 42.
At the Wanderers, the Central Gauteng Lions claimed a one-wicket win in a low-scoring clash against the Northerns Titans.
The Titans were bowled out for 145 in 38.2 overs, with opener Gihahn Cloete left stranded on 62*.
Bjorn Fortuin was the Lions’ chief destructor with the ball, taking 5-34 in nine overs.
The hosts appeared to have botched the run chase when they lost their ninth wicket in the 41st over with their total on 129. But Codi Yusuf (19*) and Tladi Bokako (5*) got them over the line with five overs to spare.
Mitchell van Buuren top-scored for the Lions with 44, while Neil Brand (3-22), Aaron Phangiso (2-22) and Corbin Bosch (2-32) bowled well for the Titans.
In Division 2, the KZN Inland Tuskers beat the Mpumalanga Rhinos by five wickets in Pietermaritzburg and the Limpopo Impalas beat the Eastern Storm by five wickets in Polokwane.
One-Day Cup Division 1 results:
One-Day Cup Division 2 results: