Singapore suffered their first defeat under coach V. Sundramoorthy when they were beaten 3-0 after extra time by dominant Vietnam in Monday night's final of the 2016 AYA Bank Cup in Yangon.
After a resolute Lions display kept the Vietnamese at bay throughout 90 minutes, it took just 25 seconds of extra time for the deadlock to be broken through a strike from talismanic captain Le Cong Vinh.
Eight minutes later, Nguyen Van Quyet popped up with a second for the Golden Stars before substitute Dinh Thanh Trung netted in the 114th minute to seal victory at the Thuwunna Stadium in the inaugural four nation tournament.
It denied Sundram a fairytale first trophy in charge of Singapore after victory over host nation Myanmar in his debut match on Friday.
Few would argue the Vietnamese did not deserve the trophy, given they showed the greater endeavour and intent in the final. However, it did look for a while as though Sundram was about to mastermind another of the famous smash-and-grab victories that were the trademark of his successful time in charge of LionsXII in the Malaysia Super League.
His team, however, did have the first real chance after seven minutes when Baihakki Khaizan reacted quickest to a short corner routine and met Gabriel Quak's cross with a diving header but was unable to keep it down.
However, it did not take long for Nguyen Huu Thang's side to gain the upper hand. They came close with a swerving free kick from Cong Vinh in the 34th minute that was just over before Van Quyet wastefully fired wide two minutes later after a corner had been deflected straight to him.
The chances continued to fall Vietnam's way in the second half. But Nguyen Van Toan and Cong Vinh failed to capitalise on decent openings before Hassan Sunny was alert to keep out a low strike from Van Quyet 10 minutes after the hour mark.
A minute later, Hassan was finally beaten when Cong Vinh defied the offside trap and flicked the ball over the Lions keeper. But a brilliant recovery saw Baihakki race back and somehow clear off the line, with the aid of the woodwork.
By then, Singapore's best chance of snatching a winner looked to be through set pieces. A long throw from Madhu Mohana nearly paved the way for Safuwan Baharudin to do just that, only for his goal-bound header to be blocked by Que Ngoc Hai.
So it was 0-0 after 90 minutes, with the Lions doing well to keep the impressive Vietnamese at bay.
But within the first minute of the first extra period, the scoring was finally opened when Van Quyet played a lovely through pass for Cong Vinh to run onto and fire a left-footed effort past Hassan.
Moments after spurning a gilt-edged opportunity with a tame header straight at Hassan, Van Quyet made it 2-0 in the 99th minute. He latched onto Van Toan's deflected pass and lashed an unstoppable strike into the back of the net.
Singapore, so determined up to that point, began to look absolutely deflated, despite Sundram's bid to get back into the contest by throwing defender Afiq Yunos up as an extra target man.
And six minutes from the end, the rout was complete when Van Toan was left in acres of space. He slipped a neat pass to Thanh Trung, who burst past Nazrul Nazari before clinically slotting into the bottom corner to cap off a tournament-winning display from the Golden Stars.
Singapore: Hassan Sunny, Nazrul Nazari, Madhu Mohana, Baihakki Khaizan (Afiq Yunos 102'), Hafiz Abu Sujad, Hariss Harun, Izzdin Shafiq, Gabriel Quak (Shahril Ishak 73'), Azhar Sairudin (Khairul Amri 59'), Faris Ramli, Safuwan Baharudin
Vietnam: Tran Nguyen Manh, Tran Dinh Hoang, Vu Ngoc Thinh, Que Ngoc Hai, Tran Dinh Dong, Nguyen Tuan Anh, Luong Xuan Truong (Nguyen Huy Hung 85'), Nguyen Van Toan, Nguyen Van Quyet, Pham Thanh Luong (Dinh Thanh Trung 91'), Le Cong Vinh (Le Hoang Thien 106')