Japan officials expect Akira Kaji to recover from an ankle injury in time to face Australia at the World Cup finals on June 12.
The 26-year-old right-back was stretchered off during Japan's 2-2 friendly draw against Germany on Tuesday, but the problem is not as serious as initially feared.
Team doctor Tuguo Morikawa said: "He's got a bruised right ankle but it's not so bad.
"He is now using crutches as a precaution. He just needs two or three days rest."
The news will come as a relief to coach Zico, who has already lost one of his first choice defenders, Makoto Tanaka.
The 30-year-old was forced to withdraw from the squad because of a hamstring injury and has been replaced by Teruyuki Moniwa.