Jordi Murphy has been ruled out of Ulster's Pro14 meeting with Southern Kings on Sunday.
The Ireland flanker sustained ankle ligament damage during his debut against Edinburgh last weekend.
Chris Henry is another that won't be heading for South Africa after suffering a calf strain in the Ulster 'A' game with Leinster.
Peter Browne and Jack Owens are following the return-to-play protocols having sustained concussions in that 'A' game.
In better news for Dan McFarland, Tom O'Toole, Jean Deysel, Clive Ross and Tommy O'Hagan have recovered from their respective injuries and are available this weekend.