Australia and hosts Thailand both qualified for the quarter-finals, as Group A concluded at the Asian Football Confederation Under-23 Championship.
Both countries are now a step closer to Tokyo 2020, as the age-group event offers three places in the men's Olympic Games tournament.
All four teams in the group had a chance of progressing at the start of the day, which led to a pair of nervy encounters.
The Australians drew 1-1 with Bahrain at Thammasat Stadium in Rangsit, which was enough to win the group on five points.
Ramy Najjarine gave them the lead after 34 minutes after latching onto Reno Piscopo's pass and slotting home.
Bahrain drew level three minutes into injury time at the end of the first half, as Mohamed Marhoon bent home a low free-kick.
There were no further goals and Bahrain finished bottom of the group with two points.
Thailand squeezed through behind Australia with four points, after their game with Iraq also ended 1-1 at Bangkok's Rajamangala Stadium.
Home nerves were settled in the sixth minute when the hosts were awarded a penalty via the video assistant referee.
Iraq's Najm Shwan was penalised for handball and Saringkan Promsu made no mistake from the spot.
The game was level four minutes after the break, when Mohammed Qasim poked home a close-range finish, but Iraq could find no further way through.
They ended on three points after drawing all of their matches.
Groups B and C conclude tomorrow.