Stormers and South African star winger Bryan Habana will miss up to 10 weeks of Super Rugby after tearing knee ligaments.
Habana, who moves to French Top 14 club Toulon at the end of the Super Rugby season, left the field after 55 minutes of the narrow victory over title-holders the Chiefs on Sunday.
Stormers coach Allister Coetzee confirmed the bad news in Cape Town on Sunday.
"Bryan has done his medial collateral ligament and, conservatively, he could be out for 10 weeks,'' he said.
"He could be back after seven weeks, but I would say 10 weeks.''
The southern hemisphere provincial championship season runs from February to August with a three-week break during June for Tests with Habana the first choice Springboks winger.