An unbeaten 131 from Jonathan Bird put Western Province in a strong position in their match against the Central Gauteng Lions at Newlands.
Bird was involved in an unbroken third-wicket partnership of 116 with David Bedingham (57*) as WP finished day three on 286-2, an overall lead of 314.
Bjorn Fortuin and Duanne Olivier picked up the only wickets to fall.
In Bloemfontein, the Free State Knights finished the day on 107-3 after being forced to follow on by the Northerns Titans, who declared their first innings closed on 515-9.
The Knights were bowled out for 197 in their first innings, with Jason Raubenheimer (36*) involved in a 40-run last-wicket stand with Mbulelo Budaza.
In Paarl, the North West Dragons were also forced to follow on, against the Boland, Rocks.
They finished the day on 259-7, still trailing by 56 runs, having been dismissed for 170 in their first innings.
At Kingsmead, the KZN Dolphins took a 16-run first-innings lead over the EP Warriors.
The Dolphins were 402-7 at stumps thanks to Sarel Erwee (93) and Marques Ackerman (96). Jason Smith also contributed with 46 while debutant Slade van Staden was unbeaten on 49.
Dolphins vs Warriors scorecard
Division Two:
Mpumalanga Rhinos vs Eastern Storm
