The Iranian, who has dominated the freestyle 92kg class with back-to-back world golds, had already missed the Ranking Series events in June and July after suffering the same problem, though it was on the other leg.
Abazar Eslami, a member of the Iranian coaching staff, told IRNA that Qassempour would undergo an MRI scan before the medical team makes a full assessment of his injury within the coming days.
Should Qassempour miss out on the event in the Serbian capital, he will likely be replaced by young prodigy Amir-Ali Azarpira.
Azarpira walked away with the world under-23 gold medals in 2021 and 2022, while he was part of the Iranian seniors’ team that finished second to the USA in last December’s Freestyle World Cup in Coralville, Iowa, the United States.
Mohammad-Mobin Azimi could also be considered for the 92kg slot in Belgrade after he won the ultimate prize at the U20 World Championships in Amman, Jordan, last week.
Milad Valizadeh (57kg), Reza Atri (61kg), reigning world champion Rahman Amouzad (65kg), Amirmohammad Yazdani (70kg), Younes Emami (74kg), Mohammad Nokhodi (79kg), eight-time world and Olympic medalist Hassan Yazdani (86kg), Mojtaba Goleij (97kg), and Amirhossein Zare’ (125kg) will also represent the country in the freestyle events in Belgrade, where Iran – runner-up to the USA last year – will be chasing a first freestyle crown in a decade.