Orlando Pirates missed the opportunity to close the gap at the top of the DStv Diski Challenge following a 4-2 defeat to Mamelodi Sundowns at the Giant Stadium on Saturday.
Champions Cup newcomers Stormers will lack five regulars, including Springboks Frans Malherbe, Marvin Orie and Evan Roos, when they face "fearsome" Clermont in France on Saturday.
Siya Kolisi-captained world champions South Africa hope to extend a winning run over France and end losing streaks against Ireland and England when they tour Europe in November.