Japan's Celtic midfielder Shunsuke Nakamura is doubtful for the 2010 FIFA World Cup South Africa™ qualifier against Qatar on 19 November after injuring his left knee in training, it was reported on Saturday.

Nakamura, regarded as the Japenese national team's key player, picked up the knock on Thursday and decided to skip Saturday's game against Motherwell after an MRI scan in Glasgow, sports daily Sports Nippon said.

"I feel pains in the inside of the left knee. It hurts when I try to kick a ball. I'm going to skip Saturday's game," he was quoted as saying by the newspaper.

According to the paper, doctors will give their diagnosis after Saturday and it is doubtful that Nakamura will feature in fixtures against Kilmarnock and Hamilton in the Scottish Premier League next week.

If he recovers in time, the away game against Qatar will be Nakamura's first in three weeks. "I haven't received diagnosis yet, so I'm not sure about the qualifier," he was quoted as saying.

The injury is another major blow to Japan who are expected to be without first-choice goalkeeper Seigo Narazaki after he injured his left ankle in training. Needing "two-to-three weeks" of treatment, it is doubtful that Narazaki will be fully fit for the qualifier in Doha.

Japan, former Asian champions, beat Bahrain 3-2 away in their Group 1 opener in the final qualifying round and drew 1-1 with Uzbekistan at home.

Japan stand level with Qatar on four points, trailing Australia, who have a maximum six points from two straight wins. Bahrain and Uzbekistan have one point each.