Fiorentina forward Giuseppe Rossi's injury is worse than expected after doctors discovered further damage to the ACL in his right knee.
It was thought Rossi could return to action in 6-7 weeks after a MCL injury, but Fiorentina said on Saturday that further tests have discovered "a stress to the anterior cruciate ligament previously operated on."
Rossi sought the opinion of a knee specialist in the U.S. this week to confirm the extent of his latest injury.
The striker limped off in tears during Sunday's 1-0 win over Livorno following a hard tackle from Leandro Rinaudo.
Rossi, who is from New Jersey, tore his right anterior cruciate ligament during a game for Villarreal against Real Madrid in Oct. 2011 and needed three operations before returning last May with Fiorentina.
The Italy forward was examined in Colorado by Dr. Richard Steadman, who operated on Rossi in April and Oct. 2012.
Fiorentina added that Rossi "will follow a rehabilitation program for 2-3 weeks before having another check-up."
Rossi's agent Andrea Pastorello said he was unclear what "stress" meant in the diagnosis.
"It's a word that means everything and nothing. However, the cruciate ligament has not been torn," he said. "Professor Steadman has ruled out problems for his career, which is good news."
The 26-year-old is the top scorer in Serie A this season with 14 goals in 17 matches and has returned to the Italy team. He is expected to be a key part of Cesare Prandelli's World Cup roster this year, although his participation is now in doubt.
Rossi will continue his rehabilitation in New York.