The Bok number eight suffered a recurrence of an old injury to his right knee while playing for French Top 14 side Toulon, the South Africa Rugby Football Union confirmed in a statement.
MRI scans showed he will likely require surgery to repair the damage.
No replacement has been called into the Bok squad by coach Allister Coetzee, which means Warren Whiteley is likely to continue at the back of the scrum after taking over from an injured Vermeulen, this time with an elbow problem, in the June internationals against Ireland.
Coetzee will decide after the opener against Argentina whether to add another loose-forward to the squad for their second match against the same opposition away in Salta on Aug. 27.
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(Reporting by Nick Said; Editing by Toby Davis)
