Japan midfielder Shunsuke Nakamura is confident a knee injury will not prevent him lining up against Australia on Monday.

The Celtic star's participation in Japan's World Cup opener is in doubt after he limped out of training for the second day running on Thursday.

Nakamura admitted he is worried about his tendon problem but he is determined to face the Socceroos.

"I expect to be all right for Australia. The pain should be gone by tomorrow or the next day," said the 27-year-old.

"When I shoot or push off it hurts. I'll probably be able to put more strain on it on Friday.

"We've got this machine back at the hotel I will have a go on later.

"It doesn't heat the surface but it apparently heats the deep tissue and spreads rays or whatever so I should be all right."

Japan's other injury doubt is winger Akira Kaji, who is struggling to overcome the ankle injury he suffered during last week's friendly against Germany.