Vietnam survived a second onslaught from Syria to claim the point they needed to join Malaysia in the AFC U23 quarterfinals in China.
The two nations progressed to the last eight, while 2016 Southeast Asian (SEA) Games champions Thailand were eliminated.
A goalless draw was enough for the Vietnamese to finish the group as runners-up to South Korea -- the home country of their head coach Park Hang-Seo.
The Koreans survived a fightback from Australia to win Group D's other game 3-2. South Korea now face Malaysia on Saturday, while Vietnam will play Iraq for a place in the semifinals.
As in their 1-0 victory over Australia on Matchday Two, Vietnam set out in a defensive shape against Syria, allowing them most of the possession and looking for opportunities on the break.
While the Syrians dominated, poor finishing let their opponents off the hook time and again.
In a rare attack, Cong Phuong's angle drive almost put Vietnam ahead midway through the second half, and this seemed to spur Syria into action.
A shot was cleared off the line, and Rafat Muhtadi headed wide when he looked certain to score as the Golden Dragons started to hang on.
Muhtadi then side footed wide from six yards with four minutes remaining after the Syrians had cut through Vietnam's defence.
But, like Malaysia against Saudi Arabia the previous day, Vietnam defended with determination and rode their luck a little to survive.
And when Mouhamad Anez blazed his shot over in added time, it was a clear indication that this was not going to be Syria's night.
Vietnam claimed their place in the last eight to become the second Southeast Asian nation to make it out of the group after Malaysia's 1-0 victory over Saudi Arabia clinched their quarterfinal spot.
It represents a great return for the ASEAN sides who had started the tournament as clear underdogs.
The games against South Korea and Iraq on Saturday will be hugely challenging, but Malaysia and Vietnam have nothing to lose, having already surpassed expectations.