Fiorentina have confirmed that Marko Pjaca has torn a knee ligament in his left knee in the latest injury blow for the on-loan Juventus winger.
The 23-year-old had tests on Saturday after spraining his knee during a training session.
The Serie A side have since confirmed the severity of the injury, adding that he will see a consultant in the coming days.
"Fiorentina announces that during yesterday's training session the player Marko Pjaca reported a sprain trauma to his left knee," a club statement read.
"The tests carried out this morning have shown a rupture of the anterior cruciate ligament.
"In the next few days, the player will have a surgical consultation to plan the most appropriate treatment."
It is the second time in two years that Pjaca has suffered this type of injury.
In March 2017, he had an operation after he tore the ACL and meniscus of his right knee while on Croatia duty.
Pjaca was loaned to Schalke for the second half of last season after missing the first few months of the campaign, making nine appearances for the German side.
He moved to Fiorentina on loan with the option of a €20 million (A$31.88 million) permanent move last August and has played 19 times this term for the Viola.