The Waratahs are almost certain to lose rookie winger Alofa Alofa and No.8 Wycliff Palu for their Round 8 match against the Stormers in Cape Town.
Alofa picked up a strain during training on Tuesday which has left the Waratahs back line stocks wearing thin.
Winger Alofa was on the replacements bench for the Sharks match but with Rob Horne suspended coach Michael Cheika is likely to start Matt Carraro alongside wing Peter Betham.
Wycliff Palu rolled his ankle so he is doubtful to start against the Stormers and Cheika could move captain Dave Dennis to No.8 and shift Jacques Potgieter to the back row from lock with Will Skelton beside Kane Douglas.
"(Palu) is still very swollen today, so I am planning without him," Cheika said.
The Waratahs are starting to feel the pressure on their squad depth after tough physical matches against the Brumbies, Reds, Cheetahs and Sharks.
"We're starting to get a bit low on stocks there in the backs," Cheika told the Canberra Times.
"We haven't been too bad with injuries so far, compared with some of the other teams, so that's part and parcel with what happens. We're lucky we have good depth and players who can mix in."
Last year the Waratahs beat the Stormers 21-15 at home in Sydney but this year Cheika says they will need to be more clinical in Cape Town.
"We very much set out to just keep running at them," Cheika said about last year's result.
"Sometimes we got caught up in moments where we were doing a lot of work but going nowhere, but we took a strategic point of view of 'this is how we're going to do it' and I think you'll see the same picture this week. "
"But at home against them we've got to be a bit more clinical around our ruck work and I think we'll be able to still play an attacking game."