Qatar are under the guidance of Dzmaludin Musovic, who was Osim's assistant as Yugoslavia reached the quarter-finals of the 1990 World Cup in Italy. The pair also played together at French side Valenciennes.

"He (Musovic) is a good friend of mine but that has nothing to do with the game tomorrow," said Osim.

"Qatar know everything about us but we've also been gathering information on them. Both sides have a huge pile of information, and it will be decided in the game over the 90 minutes. It's a matter of which side will play better."

Asked about the importance of the first game, the 66-year-old said: "It is important. This is the biggest tournament in Asia.

"It'll be a matter of which our players will be more; fatigued or motivated."

Japan, who won the AFC Asian Cup in 1992, 2000 and 2004, feature only two Europe-based players - Frankfurt striker Naohiro Takahara and Celtic midfielder Shunsuke Nakamura.

But they are expected to field 2006 World Cup players with the likes of Akira Kaji, Yuichi Komano, Yuji Nakata as well as Yasuhito Endo set to be in the starting line-up.

Musovic is sweating on the fitness of Al Sadd midfielder Wesam Rizik, while Sebastian Soria is also a slight concern after the Uruguay-born striker limped out of training on Saturday.

"We have a delicate situation and we must wait until the last possible moment to make decisions," said the 62-year-old coach.

"Maybe we will be able to resolve the problem with one player but I am not sure if we will be able to resolve the problem with all the players.

"We will have to decide before the game about Wesam, but I believe Sebastian will be ready for the game.

"He (Rizik) was injured during a friendly game in Thailand and maybe he will be ready to play, but the question is how long he will be able to play for.

"But a positive thing for us is that we have a large group of players. If one player is unavailable this is not a problem, we do not only have 11 or 14 players we have around 20 good players who can start in this competition."

Musovic believes Qatar are now ready to prove themselves against Asia's best following their success at the 2006 Asian Games.

"We have had six months to prepare and I have told the players it is now time for the Qatar national team to show that we can not only win in Doha and not only win against the medium teams in Asia, but against the best," he said.

"Our target is to reach the second round. Everybody believes that Japan are the strongest team and that they are the favourites for this game and the whole competition, but the result is open and nobody knows how it will finish."