On day four of the five-day domestic final at the Wanderers, play was ended due to bad light with Western Province at 99-3.
Proteas players Tony de Zorzi (38*) and Kyle Verreynne (27*) were at the crease, with Western Province still requiring another 209 runs to win.
The visitors made a good start to their run chase with a 55-run partnership between De Zorzi and Edward Moore. Moore was dismissed by Lions spinner Bjorn Fortuin for 26.
The hosts then quickly took two more wickets, with Malusi Siboto dismissing Yaseen Vallie for a duck and Fortuin catching Gavin Kaplan at bat-pad, also for nought.
Earlier, Delano Potgieter (155*) and Codi Yusuf (46) had helped the Lions reach a total of 394 after being 113-6 and then 159-7.
WP sets a challenging 308.