Japan midfielder Shinji Ono returned to Japan on Thursday to undergo medical examinations on his left ankle and may need surgery depending on the results, soccer officials said.
The Feyenoord player aggravated his ankle injury in a league match at ADO Den Haag last weekend when he was fouled in the 39th minute and was substituted at halftime. Sunday's match was the team's final before the Dutch league entered the winter break.
"It's not like the pain is getting worse," said Ono.
"But if it needs to be operated on, I might as well do it now," he said.
Ono is expected to be sidelined for about six weeks if he has surgery and is doubtful for Japan's clash at home with North Korea on Feb. 9 in their opening match of the Asian zone qualifying round for the 2006 World Cup in Germany.