Perpignan will be minus three players, including South African wing Wandile Mjekevu, for their two Heineken Cup Pool showdowns against Munster.
USAP travel to Thomond Park on Sunday before hosting the two-time former European champions just a week later in Pool 6 of the tournament.
Mjekevu has a sprained ankle and will be out for three weeks, his club revealed on Monday.
French second-row Romain Taofifenua, who has a twisted knee, will also miss three weeks while Georgia prop Giorgi Jgenti faces six weeks on the sidelines with a fractured wrist.
All three were injured in Friday's 30-23 defeat at home to Clermont.
Centre David Marty, who has a calf injury, and English number eight Luke Narraway, who has a hip problem, both also came off against Clermont and will miss the trip to Munster.
They should be fit for the return match on December 14.
USAP already had a selection headache with six other players on the treatment table while New Zealander centre Lifeimi Mafi and Tonga prop Sona Taumalolo are both suspended.
All four teams in the Pool have won one and lost one of their two matches so far.