The Vietnamese squad yesterday made it four wins after they beat hosts Myanmar 1-0 in the last qualifying round's Group G match at the Youth Training Centre, Yangon City.
The score was opened by Ha Duc Chinh in the 20th minute.
Pham Trong Hoa, who suffered a knee pain during a training session on Sunday, broke the Myanmar defenders and gave a perfect pass to Chinh who sprinted to the box and shot to goalkeeper Phone Thitsar Min's right corner.
It was one of many chances that Chinh received through the first half. Earlier he missed a clear opportunity when he was alone in the box but his kick found the goalie's position.
Striker Nguyen Tien Linh tore the net at the 13th mark but it was an offside trap.
Vietnam had a golden chance to double the result just 10 minutes after the interval.
Goalie Min downed Chinh in the box and the visitors were given a penalty. However, Captain Nguyen Trong Dai's shoot-out hit the bar.
Myanmar played much better in the second half. They created numerous problems for the Vietnamese defenders with a lot of long-distance shots, but most of them were off target.
They had more ball possession and met with no challenge to block Vietnam's attacks.
In their previous match against Hong Kong, Myanmar scored a double in the last minutes including additional time to come from behind to win 2-1.
However, they could not repeat it yesterday and accepted their loss, which placed them second in the ranking. They have to wait for the results from the other group to know if they can qualify for the finals.
In the previous four meets, Vietnam were always the winners.
In another match of the group on October 6, Hong Kong beat Brunei 5-0.
In Group J, six-time runners-up Japan became the first side to punch their ticket to the finals after downing second-placed Australia 3-0 in their final match at the National Sports Complex Stadium in Vientiane, Laos.
Two goals including a penalty in the space of two minutes in first half stoppage time laid the foundations for the Japanese to record a perfect record of three wins from their trio of qualifying games.
Later, Iraq trounced Bahrain 4-1 to finish top of Group F and qualify for the finals.
Other group matches were played later on October 6 and early this morning in Hanoi time.
Ten group winners and five best second-placed teams will qualify for the finals, while hosts Bahrain receive an automatic qualification.
If Bahrain finish on top of their qualifying group or among one of the five second best-placed teams, the next second-placed team will qualify for the final competition.