FC Tokyo striker Yoshito Okubo has been diagnosed with a right-foot ligament injury and will need four to six weeks for a full recovery, team officials announced Tuesday.

Okubo, the J1 career scoring leader with 177 goals, was hurt in Sunday's game against Jubilo Iwata at Yamaha Stadium and replaced after 23 minutes.

"He was our main attacking guy, so (his absence) hurts us. I hope we can gain as many points (in the league) as possible in the meantime," FC Tokyo manager Yoshiyuki Shinoda said.

The 35-year-old former Japan striker joined FC Tokyo in January after four years with Kawasaki Frontale. He has a team-high six goals in 15 games this season.