The 24-year-old Beelen collided with Gent's Helio Varela and appeared to be in serious condition immediately after. Players from both teams retreated to the locker rooms, visibly shaken by the injury. Beelen underwent surgery that same evening, which the club described as "successful" in a statement released on Monday.
Feyenoord has not revealed the extent of the injury or provided a timeline for Beelen's recovery.
Watanabe nearing
Beelen's injury has led Feyenoord to accelerate efforts to secure a central defender. Vice-captain David Hancko is close to transferring to Saudi Pro League team Al Nassr for a club-record fee of €40 million.
Gent's Tsuyoshi Watanabe has been identified as Hancko's replacement and is reportedly on the verge of joining Feyenoord. De Telegraaf reports that Gent is asking for €8 million for the 28-year-old Japanese international.