TOKYO, June 25 - Japan's Asian Cup preparations have gone from bad to worse after only 10 players turned up for the squad's training camp.

Only eight of coach Ivica Osim's preliminary squad of 30 were able to practice on Sunday, with two players injured and 20 opting to stay with their clubs.

With J-League games taking place at the weekend, clubs and players were entitled to make their own decision about the camp, but the extraordinary number of stay-aways will have alarmed the Bosnian.

Celtic midfielder Shunsuke Nakamura was one of the few players who braved the pouring rain, putting training ahead of a family get-together on his 29th birthday.

"I don't know how many more birthdays I'll have as a Japan player," Nakamura was quoted as saying in Monday's Japanese media. "I just hope I can bring some creativity and experience to the side."

Osim has already slammed Japan's Asian Cup preparations as a joke, blaming the J-League schedule for a lack of time together with his players.

The 66-year-old is upset that most of his players have club commitments before Japan's Asian Cup opener against Qatar on July 9.

The Asian Cup holders will assemble for a final three-day training camp before flying to Vietnam on July 4 for their Group B games in Hanoi.

The United Arab Emirates and co-hosts Vietnam are also in the same group as the defending champions.

Japan will be bidding for a third straight Asian Cup title after winning campaigns in 2000 and 2004.

This year's tournament takes place from July 7-29 and will be staged jointly by Vietnam, Indonesia, Thailand and Malaysia.