Jamie Joseph has been dealt a double blow with Highlanders pair Patrick Osborne and Craig Millar set to fly home from South Africa.
Both players feature in the 34-18 win over the Sharks in Durban last weekend.
Osborne reaggravated an ankle injury first picked up against the Blues at the beginning of the season, while Millar picked up a shoulder injury.
Argentina prop MatÃas DÃaz has been flown in as front row cover.
This weekend's match against the Stormers should also see prop Craig King win his 100th cap for the franchise, after making his debut back in 2005.