In the lead up to the tournament in Cambodia, coach Tony Vidmar cautioned against complacency and stressed that every team is a threat.
It seems his advice wasn't heeded, as the Joeys failed to keep a clean sheet and could only draw against less-fancied Myanmar at Phnom Penh's Army Stadium.
The draw was the first time Australia's youngsters had failed to defeat Myanmar in five attempts.
Australia will next face Vietnam in Group A on Tuesday followed by matches against Philippines, Singapore and Malaysia.
Defending champions Thailand, who inflicted a 3-2 defeat on the Joeys in this tournament last year, are in Group B.
