The fitness of Japan captain Wataru Endo, Yuta Toyokawa and Masashi Kamekawa will be a game-time decision for Tuesday's Asian Under-23 Championship semifinal against Iraq, according to the Japan Football Association.
The trio trained apart from the team on Sunday. Endo complained of discomfort in his left groin, Toyokawa in his hip and Kamekawa in his left hamstring.
Japan can qualify for its sixth consecutive Olympics in men's soccer if Makoto Teguramori's side beats Iraq. If Japan loses, its last shot at this summer's games in Rio de Janeiro will be in the third-place match on Friday.
Endo said he had actually been nursing the injury before Friday, when Japan defeated Iran 3-0 in extra time in the quarterfinals. The new Urawa Reds man stressed the injury was not serious.
"It hasn't gotten any worse," Endo said. "Ultimately, the coach will decide. I'll try to be as ready as I can be."
Teguramori, though, will be relieved to have Musashi Suzuki back after the Albirex Niigata striker missed the Iran game due to inflammation in his groin.
Suzuki took part in training in full on Sunday, declaring himself fit to go.
"There's no problem now," he said. "The part that was sore is fine as well as the rest of the body. I'll just go out and do my job once I'm in the game. I'll do whatever it takes to help the team win."