The World Cup-winning Springbok, 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 Saturday.
"Bryan has done his medial collateral ligament and, conservatively, he could be out for 10 weeks," Coetzee said on Sunday.
"He could be back after seven weeks, but I would say 10 weeks."
29-year-old Habana, who has amassed 83 caps, has scored 47 Test tries along the way in establishing himself as one of the most prolific finishers in the world game.
The southern hemisphere provincial championship season runs from February to August with a three-week break during June for Tests.
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