It is feared the legendary Argentine defender, who will turn 40 in August, has ruptured his Achilles tendon, putting his hopes of continuing for another season in doubt
The veteran Argentine, who turns 40 in August, was stretchered off from the field just 17 minutes into the game at the Renzo Barbera after a collision with Rosanero defender Salvatore Aronica.
According to early unconfirmed reports, Zanetti has suffered an Achilles tendon injury, which, according to Dr. Piero Volpi, would put the right-back's career in jeopardy.
"If it proves to be the case, it would be difficult for him, at 40 years of age, to be able to return from," he told Novastadio.
Inter lost the game 1-0, with Josip Ilicic scoring what proved to be the winner just seven minutes before Zanetti's injury-enforced exit.
The defeat leaves the Nerazzurri seventh in Serie A, two points behind fifth-placed Roma and eight adrift of Fiorentina, who occupy Italy's third and final Champions League berth.