Stormers lose Malherbe
Malherbe will be sidelined for two to three weeks after suffereing a neck injury in South Africa's win against Ireland in Port Elizabeth at the weekend.
The injury means young tighthead prop Wilco Louw is part of coach Robbie Fleck's 27-man squad.
The Stormers will also be without their other co-captain, Juan de Jongh, who is on Springbok Sevens duty. Fullback Cheslin Kolbe is also on national Sevens duty.
The Cape side will be led by veteran loose forward Schalk Burger for their matches against the Melbourne Rebels and Western Force.
The other additions to the squad see fit-again lock Jean Kleyn, prop JP Smith and utility backs Jaco Taute and Scott van Breda all join the touring group for the first time this season.
Fleck said that it is vital for the team to gain some momentum following the June International break.
"This is obviously a crucial tour for us, and the players know that we are in for two challenging matches in Australia.
"With our international players only joining us this week, we have had to travel later than we usually would, but the benefit of that is that we are travelling together as a united group.
"We have set ourselves some goals for this trip, one of which is for these young guys to gain some valuable experience playing abroad.
"We have to gain some momentum in this final phase of the competition to keep our destiny in our own hands," he said.
The Stormers coach said that while it is disappointing to lose the services of Malherbe and De Jongh, the team will be in secure hands on the pitch under Burger's leadership.
"Schalk Burger is one of the most experienced players in South African rugby, and he is certainly no stranger to the captaincy role, so we will draw on his leadership abilities as much as we can," he said.
Fleck said that despite the unique challenges of travelling so late in the season and leaving late in the week, the squad is excited to make the most of their time in Australia.
"Having a tour this late in the season was always going to be a challenge, but traditionally we are good tourists and a big part of that success has been our ability to get tight as a group and to make the most of our time away.
"We are looking at this tour as a great opportunity to pull together, tick a lot of boxes both on and off the pitch and build the momentum we are looking for," Fleck added.
Stormers touring squad: Schalk Burger (captain), Nizaam Carr, Damian de Allende, Daniel du Plessis, Jean-Luc du Plessis, Pieter-Steph du Toit, Eben Etzebeth, Rynhardt Elstadt, Nic Groom, Huw Jones, Oliver Kebble, Jean Kleyn, Vincent Koch, Siyamthanda Kolisi, Wilco Louw, Bongi Mbonambi, Sikhumbuzo Notshe, Siyabonga Ntubeni, JD Schickerling, Louis Schreuder, JP Smith, Jaco Taute, Brandon Thomson, Scott van Breda, Kobus van Wyk, Alistair Vermaak, Leolin Zas.