Thailand dominated the game from the start with consecutive attacks and created their first chance in the 5th minute when Arthit Sunthornphit nearly scored.
Vietnam gradually got into the game after the 20th minute. Forward Phan Thanh Binh had three clear chances but was slow to apply the finishing touch.
Goal keeper Nguyen Tan Truong played well for most of the match except for the 72nd minute when Keerati Keawsombut pounced on a ball that rebounded off Truong.
The setback did not discourage the Vietnamese. They continued pressing ahead and forcing Thailand to play in defence and the equalizer came from a rapid counter-attack.
Captain Pham Thanh Luong was fouled inside the penalty area and Hoang Dinh Tung sent the Thai goalkeeper the wrong way with a shot to the left corner.
In the next match on November 4, Vietnam will face East Timor, who lost to Malaysia 11-0 in the earlier game.