The three-week festival should give an indication of the advances made by the continent after last year's World Cup where Japan, South Korea, Iran and Saudi Arabia all failed to get past the first round.

Confederation newcomers Australia were the only standout.

If the last Asian Cup in 2004 is any guide, there is plenty to look forward to.

In China three years ago, coaches were sacked, fans got ugly, players brawled, 17 red cards were shown and politics were dragged into the mix.

Thailand host Iraq in the opening game at the Rajamangala National Stadium here on Saturday, with organisers anticipating a full-house and an entertaining showpiece to kick off the tournament.

Security has been beefed up, with police issuing reassurances that the safety of players and fans is paramount in a country ruled by a military junta.

"We are confident it will run smoothly as the participating countries are not rivals. We don't expect anything bad or serious to happen," said Lieutenant General Phanu Kerdlarpbhol, deputy head of Bangkok's metropolitan police.

Aside from security, hosting the championships in four different countries has created logistical headaches for the Asian Football Confederation, with four football associations to deal with and four media centres to be accommodated.

The governing body insist it is all systems go, although they are unlikely to repeat the multiple-host exercise any time soon.

Australia, Japan, South Korea, Saudi Arabia and Iran are expected to be the main challengers in the 16-team, 32-match tournament.

The Socceroos have brought a star-studded squad for their first outing in Asian football since defecting from the Oceania confederation last year, and open their account against Oman here on Sunday.

Coach Graham Arnold, who is preparing the side under the potential of being dumped after the tournament in favour of a higher-profile candidate in time for 2010 World Cup qualifiers, believes his side is hungry to win.

"A pass is reaching the semifinals, but I'll put pressure on myself by saying a failure is not making the final," he said ahead of the tournament.

Defending champions Japan will be looking to Scottish Player of the Year Shunsuke Nakamura to steer them into the knockout rounds, although coach Ivica Osim warns his side are tired and could flop.

"You may be unconditionally expecting us to come home after the final on July 29 but there is the possibility that we will come home after just three (group) matches," he said this week.

Despite his apprehensions, Japan should sail through Group B leaving United Arab Emirates, Qatar and co-hosts Vietnam to fight for second place.

China, with coach Zhu Guanghu's job hanging by a thread, have had a miserable lead-up with defeats to Thailand and two American league sides.

But with their European-based players, led by captain Zheng Zhi, all available fortunes could turn, and Zhu insists China's preparations are on track.

"We're preparing step by step to get ready for the Asian Cup. We're on track," he said.

China reached the final of the last regional showpiece in 2004 but have failed to build on their success, dropping nearly 30 places in the FIFA rankings and failing to reach last year's World Cup.

They play co-hosts Malaysia on Tuesday before facing an in-form Iran and Uzbekistan in a tough Group C.

In Group D, an injury-hit South Korea, the 2002 World Cup semifinalists, have their work cut out against triple champions Saudi Arabia, 2004 semifinalists Bahrain and co-host Indonesia.