Gerhard van der Heever is flying to Australia to join the Stormers squad as a replacement for the injured De Kock Steenkamp.
Lock Steenkamp suffered a sternum injury in Friday's defeat by the Auckland Blues and will be out of action for up to a month.
He is returning home from the Stormers' tour immediately but with Eben Etzebeth having returned to full fitness, coach Allister Coetzee decided to call up an extra back in winger van der Heever, who lost his place in the squad when he went down with a knee injury.
Etzebeth is set to take over from Steenkamp against the Waratahs in Sydney next weekend, and Coetzee also has recent call-up Don Armand available after he arrived as a replacement for Michael Rhodes.
Coetzee said: "Yes, it's not like for like - with a wing replacing a lock - but we feel we're well covered up front, with Eben back to fitness and Don having been here for a week now.
"Having Gerhard join us will give us some more options out wide in our two remaining tour games.
"Eben is ready to start for us, after making his return against the Blues, but unfortunately, it seems to be a case of 'one in, one out' for us at the moment - first losing Michael and now De Kock, but flying Don in and now having Eben back to full fitness.
"He did well against the Blues, in his first appearance of the 2013 Super Rugby season, and we're looking forward to him adding more value as the tour progresses.
"Gerhard had been playing some great rugby this season, but he has recovered well. He very nearly came into contention for the tour squad from the start, so we look forward to welcoming him back into the fray."