Japan's Asian Cup preparations have suffered a major blow after influential defender Marcus Tulio Tanaka revealed Monday he will need three weeks to fully recover from a left knee injury sustained on the weekend.

Tulio, who hurt the knee in the first half of Urawa Reds' 1-0 win at Shimizu S-Pulse in the J. League, visited Japan's training camp in Chiba Prefecture to inform coach Ivica Osim.

The injury has cast a cloud over Japan's bid for a third straight title at the July 7-29 tournament in Southeast Asia, but Tulio said he has not given up hope of being fit in time for Japan's opener against Qatar in Hanoi on July 9.

"I believe in miracles. I'll just have to dedicate myself to getting back to fitness," said Tulio, the 2006 J. League Player of the Year.

Coach Osim has already expressed concern at the lack of time the Japanese have to prepare because the J. League runs through this weekend and he feels player burnout could harm their chances of a three-peat.