Le Cong Vinh nodded in a dramatic stoppage-time equaliser as Vietnam were crowned Asean champions for the first time after clinching an aggregate victory over three-time winners Thailand in the AFF Suzuki Cup final in Hanoi.
The Vietnamese held the advantage after a stunning 2-1 win in the first leg in Bangkok, but Teerasil Dangda drew the sides level overall with a 21st-minute header.
But with the match looking destined for extra-time, Cong Vinh met Nguyen Minh Phuong's free-kick with a header that looped over goalkeeper Kosin Hathairattanakool to spark wild celebrations from the capacity crowd at My Dinh National Stadium.
Both teams struggled to find their footing on the greasy, rain-soaked pitch early on and there were no real efforts on goal until the 11th minute when Cong Vinh's cut-back from the left by-line found Doan Viet Cuong who blasted over from the edge of the Thai box.
The home side appeared happy to sit back and defend their first-leg advantage but found their first-leg lead wiped out when Vu Nhu Thanh failed to track the run of Teerasil, who charged into the box to head a Sutee Suksomkit free-kick from the right past Duong Hong Son.
The home side were stunned and were unable to muster a response until the 32nd minute when Cong Vinh received the ball on the left flank and cut in before curling an effort just wide of the far post.
Vietnam's best chance of the half arrived in stoppage time when skipper Phan Van Tai Em scooped the ball into the box for Huynh Quang Thanh, who escaped his marked but fired wide from six metres out.
The hosts began to exert greater control at the start of the second half but the Thais went close to taking the aggregate lead on the hour when a quick break produced an opening for Natthapong Samana, whose low shot from 25 metres was turned around the post by Hong Son.
Le Tan Tai went close for Vietnam in the 66th minute with a shot from the left edge of box that was deflected narrowly wide of the far post and, a minute later, Cong Vinh snuck between two defenders to reach a deep cross from the left but put his volley just wide.
The Vietnamese appeared to tire in the closing minutes and were fortunate not to concede again as Teerasil just failed to reach a corner by Arthit Sunthornphit and Ronnachai Rangsiyo saw his header cleared off the line by a defender.
The teams looked set to battle for another 30 minutes but deep into stoppage time, Cong Vinh won a free-kick on the left flank after being tripped by Suree Sukha.
The Vietnam striker then stole a march on his marker to cleverly flick Minh Phuong's free-kick up and over the head of Kosin and into the far corner of the net with the last action of the match.
Thailand coach Peter Reid was left to reflect on what might have been after a dramatic late strike by Le Cong Vinh saw his side lose 3-2 on aggregate to Vietnam in the AFF Suzuki Cup final.
"It was a difficult game all the way until the last minute," said a shell-shocked Reid. "It was a cruel blow but hopefully, we will learn from it."
Reid's attention will now turn to the Asian Cup qualifiers, which begin for the Thais on January 14 when they visit Amman to face Jordan.
But after a gruelling and ultimately disappointing Suzuki Cup campaign, the Englishman is keen to give his charges some time off.
"Certainly, we've had better days although the rest this week will be good for the players," he said.
The Vietnamese appeared to have squandered their opportunity after Teerasil's 21st-minute opener wiped out the 2-1 advantage that they had built in the first leg in Bangkok.
But Cong Vinh's dramatic goal erased all of the disappointments of the past for the Vietnamese, who lost to Singapore on home soil in the 1998 Asean Championship final and have been beaten in the South East Asian Games football final by the Thais on four occasions since 1995.
"I'm feeling overjoyed at the moment. And we will have a private celebration with the players and with those who are close to us," said the team's Portuguese head coach Henrique Calisto.
"But the difference with this team is that they believe in themselves and they fought all the way until the end."