And Celtic face a further blow after it emerged countryman Koki Mizuno also faces surgery.

After taking painkillers to get him through Japan's World Cup fixtures over the summer, the discomfort has increased to the point where Nakamura needs further treatment.

"I've had pain from my groin, an ankle and a calf since the end of last season," he said. "The calf and ankle have been getting better in recent weeks.

"While I was playing for Japan, I took pain-relieving medicine. But it got worse."

Mizuno, who came off the bench to feature for Celtic in the friendlies against Fulham and Southampton, missed their Algarve Cup clash with Middlesbrough.

The January transfer window signing said he picked up a knee injury during a reserves clash with Gretnas last season.

"It's got so bad I can't play any longer," he said.