First Round: The Maldives withdrew before the final draw, leaving 25 teams to be divided into 6 groups of 4 or 5 teams each. The teams played against each other on a home-and-away basis, except in Group 4, where the teams played against each other twice in South Korea and Singapore. The group winners would advance to the Final Round.
Final Round: The 6 teams played against each other once over a 16-day period based in Singapore. The group winner and runner-up would qualify.