Defender Yasuyuki Konno is set to miss Japan's World Cup opener against Cameroon after suffering a knee injury in Friday's 2-0 defeat by Ivory Coast.

The FC Tokyo defender injured his right knee during the second half of Japan's final World Cup warm-up following a challenge by Arsenal's Emmanuel Eboue. Konno is set to be sidelined for two weeks, which would rule the 27-year-old out of the June 14 opener.

"It is ligament damage so it's doubtful he will play in the first game," said Japan coach Takeshi Okada. "This kind of injury normally takes two weeks to heal."