Japan beat Singapore 1-0 after a goal from striker Keiji Tamada on Wednesday preserved their 100 percent record in the Asian 2006 World Cup qualifiers.

The result was meaningless as Japan, who finished top of Group Three with six wins in six games, had already booked their spot in next year's final round of Asian qualifiers.

Tamada latched on to a defence-splitting pass from Masashi Motoyama in the 13th minute and finished from a tight angle.

But the Asian champions, who were without their Europe-based players, again failed to impress in front of 59,000 in Saitama after struggling to beat Singapore 2-1 away in March.

"It wasn't a very good performance," said Tamada. "We can't be satisfied with that. We should have played better and there's lots for us to improve on."

Real Mallorca-bound striker Yoshito Okubo had an effort harshly ruled out for offside after coming on as a second-half substitute even though replays showed it should have stood.

Japan's Brazilian coach Zico had wanted to call up several ex-internationals, such as Kazuyoshi Miura and Masashi Nakamura, but was forced to back down after fierce opposition from J-League clubs and within the Japan Football Association.

A total of 16 matches will be played in the final round of matches in the second stage of Asian qualifying on Wednesday.