OEHRINGEN, Germany, June 8 - Harry Kewell declared himself fit and ready to play in Australia's opening World Cup match with Japan after clearing two major hurdles.

Kewell was in danger of missing Monday's Group F match in Kaiserslautern after injuring his groin in Liverpool's FA Cup win over West Ham last month.

He missed Australia's victory over European champions Greece and last weekend's draw with the Netherlands but made his international return ahead of schedule in Wednesday's 3-1 win over Liechtenstein.

He was substituted after 60 minutes and told by coach Guus Hiddink that he needed to prove his fitness by completing a two-hour training session on Thursday, but passed the test with flying colours.

"The groin's all right," he told the assembled media.

"We all sat down and decided I was going to play 60 minutes (against Liechtenstein) and I got through that fine.

"It was important for me to play in the game then back up (repeat) in the training session today and that's what we did.

"We achieved that now and now we've got the game to look forward to."

Kewell's speedy recovery is a major boost for the Australians ahead of Monday's crucial clash with Japan.

With Brazil and Croatia also in the group, a defeat for either Australia or Japan would significantly harm their prospects of reaching the second round.

Hiddink said Kewell would definitely play some part against Japan but has still not decided whether he will start or come off the bench.

Kewell was replaced by Josh Kennedy against Liechtenstein and the move paid off when the towering Kennedy climbed above two defenders to score on debut, giving Hiddink the option of employing his extra height against Japan.

Kewell said Hiddink had still not told the players what he was planning but had warned them to expect a tough match against the Japanese.

"They're a great team because they're at the World Cup," Kewell said.