Kawasaki Frontale announced a pair of long-term injuries to key players Akihiro Ienaga and Michael James Fitzgerald.
Both were absent for their side’s costly 3-0 Tamagawa Clasico defeat to FC Tokyo at the weekend, and the worst has now been confirmed.
Midfielder Ienaga is expected to miss a month of action after suffering from a bone fracture and bruising in his right foot.
Meanwhile, defender Fitzgerald will be out for five months after tearing the meniscus in his right knee.
Both players are in their first season with Frontale after joining the club this winter.