Dragan Mladenovic has completed his loan move from Rangers to Real Sociedad after undergoing a medical on Thursday.
Sociedad were given special permission by the Spanish FA to sign a player outside the transfer window because of an injury crisis.
Mladenovic joined Rangers from Red Star Belgrade for £1.2m in the summer, but failed to make an impact in Scotland.
Mladenovic’s Serbian international team-mate Darko Kovacevic told the Real Sociedad website: “He is happy and looking forward to coming over here because he has not been playing over there.
“He is the sort of player who could be very good for us. He has got a good engine and he is skilful.”