The Stormers suffered two tour-ending injuries after last weekend's 13-14 Super Rugby loss to the Crusaders in Christchurch.
Hooker Scarra Ntubeni (torn calf muscle) and prop Pat Cilliers (rib cartilage) will have to head home, joining Rynhardt Elstadt who returned to Cape Town last week, whilst prop Frans Malherbe (broken baby toe) and utility forward Michael Rhodes (shoulder) are in doubt ahead of Friday's second tour match against Chiefs in Hamilton.
Ntubeni has a grade two tear and could be out for five weeks while Cilliers could be sidelined for up to six weeks. Malherbe and (houlder) will be given until Wednesday to prove their fitness.
Full-back Jaco Taute (AC Joint) is making good progress from the weekend and has a big chance of facing the Chiefs.
Boland prop Martin Dreyer will fly over as injury cover and negotiations are presently underway to secure Martin Bezuidenhout, who was part of the squad last week, as cover at hooker. If Bezuidenhout cannot make it, WP Vodacom Cup hooker Stephan Coetzee will fly over as cover.
Stormers boss Allister Coetzee expressed his frustration at his side's growing list of casualties.
"It's a long list of injuries, Scarra and Pat will join quality players like Rynhardt Elstadt, Eben Etzebeth, Manuel Carizza, Jean Kleyn, Juan de Jongh and Cheslin Kolbe back home and on the sidelines," he told the Stormers' official website.
"But the guys are still positive and there's a good feeling in the camp. We had a good training session today and also had a good video review of the game.
"There were a lot of positives from the game, but the big negative - again - was us not taking the opportunities we created for ourselves."