Sosa, who has five Argentina caps, has been loaned to Estudiantes by Bayern Munich until June 30 but the club from La Plata have so far been unsuccessful in trying to obtain his FIFA clearance before the transfer window.
The 24-year-old, who joined Bayern from Estudiantes for $8.9 million in 2007, has yet to play for the Argentine club since returning to them at the end of October.
Estudiantes were allowed to take centre back Rolando Schiavi on loan from Newell's Old Boys in mid-year due a glut of injuries to defenders. He played four times for Estudiantes, helping them win their two-legged Libertadores Cup semi-final and final.
The December 9-19 club tournament brings together the champions of FIFA's six confederations with Estudiantes and European Cup holders Barcelona given a bye into the semi-finals.
Estudiantes, captained by Argentina midfielder Juan Sebastian Veron, posted their squad on the club website.
Squad:
Goalkeepers: Damian Albil, Cesar Taborda, Roberto Fernandez
Defenders: Clemente Rodriguez, Christian Cellay, Leandro Desabato, German Re, Agustin Alayes, Marcos Rojo, Juan Manuel Diaz
Midfielders: Enzo Perez, Rodrigo Brana, Juan Sebastian Veron, Leandro Benitez, Maximiliano Nunez, Matias Sanchez, Marcelo Carrusca, Juan Huerta
Forwards: Mauro Boselli, Juan Manuel Salgueiro, Jose Sosa, Jeronimo Morales Neumann, Leandro Gonzalez.
