Barcelona, Sep 23 (IANS): FC Barcelona has announced its Brazilian player Rafael 'Rafinha' Alcantara would be sidelined for six months after he successfully underwent a cruciate ligament right knee operation.

"Rafinha has been operated on successfully by doctors Ramon Cugat and Ricard Pruna following the cruciate ligament right knee injury that he suffered in the game against AS Roma," the Spanish club announced in a statement on its website on Tuesday, reports Efe.

The midfielder sustained the injury after a strong tackle by Belgian Radja Nainggolan of AS Roma in the first match of the UEFA Champions League tie, which ended 1-1.

"The player is expected to be out for around six months," the statement added.

Barcelona had to ask the Spanish Football Federation and FIFA to allow the Catalan club to register Turkish player Arda Turan to replace the Brazilian midfielder because of sanctions imposed on the Spanish club not to sign new players until January, 2016.