Stormers coach Allister Coetzee has confirmed that Jantjies will not be available for selection due to a knee injury.
After the Stormers match against the Sharks they have a bye next weekend and then head to New Zealand to play the Hurricanes.
The Stormers also have the Blues, Waratahs and Rebels on tour and coach Coetzee expects to have Jantjies available for the tour.
Jantjies missed training last week with a chest injury but still played in the Stormers loss to the Cheetahs in Bloemfontein.
Peter Grant is still out injured so Gary van Aswegen is expected to start against the Sharks.