Toulouse and Argentina second rower Patricio Albacete needs surgery on an eye-socket injury and will be out of action for a month.
"Albacete neeeds an operation and he'll need 30 days to recover," the UAR confirmed.
Toulouse had originally asked Argentina to leave Albacete at his club for a key Top 14 clash with local rivals Montpellier next weekend on the eve of Argentina's Test with Wales in Cardiff.
But in Thursday's Top 14 game with Racing Metro he took a nasty knock.
The UAR have also freed two key Biarritz players - prop Marcelo Kodela and centre Marcelo Bosch - for their clash with Perpignan on November 10.
They too miss the trip to Cardiff but will be free for the game against France in Lille November 17.
On a happier note, Argentina have recalled former captain, 35-year-old Felipe Contepomi, who last played for the Pumas in the 59-10 thrashing by France in June.
Albacete will be replaced by Tomas Vallejos, and Kodela and Bosch by Argentina-based Juan Gomez and Contepomi respectively.