The 27-year-old, whose pinpoint kicks and passes helped Celtic to the Scottish Premiership title, skipped a shooting session on Wednesday and left the ground with a thick bundle of ice strapped round his left thigh.

"He felt something funny in his left hamstring and we told him to rest up and play it safe," Japan team doctor Tsuguo Morikawa said.

But Japan press officer Ichirota Fukushi said he noticed 'nothing wrong in the way Nakamura walked' early Thursday and he was still scheduled to take part in the day's practice session in the afternoon.

The left footer, who plays a key midfield role with Bolton's Hidetoshi Nakata in a deeper position, is the latest addition to Japan's growing list of fitness doubts which included their first-choice strike duo and both wings.

He kicked 15 shots in the Wednesday morning session but only one of them went in.

Nakamura, whose successful first season in Scotland followed three years with Italy's Reggina, has been hampered by a slight cold and suspected hay fever since the Asian champions arrived here two weeks ago.

His left thigh had already been battered in Japan's 5-4 friendly home win over Honduras last September.

Nakamura told the Nikkan Sports daily that he was practicing low-flying, curling corner kicks against Australians who have a height advantage of six centimetres over Japan.

"If the kick has a low and fast trajectory, it may provoke an own goal," he said. "It will be good enough if one of us can lash a rebound into the net."

Right winger Akira Kaji, the most serious on Japan's injury list, resumed running on Wednesday for the first time since he hurt his right ankle in Bastian Schweinsteiger's violent tackle from behind in Japan's spirited 2-2 draw against Germany last week.

Strike duo Naohiro Takahara, who has left Bundesliga side Hamburg for Eintracht Frankfurt, and former Messina forward Atsushi Yanagisawa were both injured in the German game and did not play in the 1-0 win over Malta.

Takahara, who scored twice against the hosts, did play in a mini-game on Wednesday while Yanagisawa underwent a separate menu of running, passing and light shooting.

Brazilian-born left winger Alessandro "Alex" Santos, who twisted his left ankle in the win over Malta on Sunday, rejoined the rest of the squad in training but refrained from shooting practice.

Santos warned Australia coach Guus Hiddink that his defense will be "impregnable to Australian attacks."

"It is because I am too strong," said the 28-year-old, who became a naturalised Japanese to compete in Japan's second World Cup finals campaign in 2002 when they reached the round of 16.

"I hope the head coach of the other side read about what I said," quipped Santos.

Japan coach Zico has vowed to guide the Asian champions to their best-ever World Cup, hopefully to the semi-finals, since their winless debut in 1998 - they made the second round four years ago under Philippe Troussier.