Janneman Malan scored 132 as the Boland Rocks posted 332 on day one of their match against the EP Warriors in Paarl.
Malan was involved in a 111-run third-wicket partnership with an aggressive Stiaan van Zyl (91 off 92 balls).
Glenton Stuurman took 5-72 for the Warriors, who were 52-2 at stumps.
In Centurion, Western Province were bowled out for 328, with Kyle Verreynne scoring 87 and Mihlali Mpongwana 77.
Beuran Hendricks then dismissed Dean Elgar and Sibonelo Makhanya for ducks as the Northerns Titans ended the day on 1-2.
In Bloemfontein, the North West Dragons were 94-1 when rain stopped play, with Grant Mokoena on 78*.
