Co-hosts Vietnam stunned United Arab Emirates 2-0 with two quick-fire second-half strikes in their Asian Cup Group B opener on Sunday.
Goals from Huynh Quang Thanh and Le Cong Vinh sparked wild celebrations for Vietnam, who are making their first appearance in the finals since a team from South Vietnam competed in the 1960 finals and lost all three matches to hosts South Korea, Israel and Taiwan.
"We were a little lucky but we deserved to win," Vietnam coach coach Alfred Riedl told Reuters. "This has already caused a sensation but it's only one win."
The Austrian added: "I can't go around shouting about this too much. We are not a big team but we never go out to lose a game."
Striker Faisal Khalil should have put UAE ahead in the 25th minute but the Didier Drogba lookalike was denied by a fingertip save from goalkeeper Duong Hong Son.
However, the home side took a surprise lead in the 63rd minute when defender Thanh volleyed home after an embarrassing mix-up in the UAE defence.
Vinh doubled Vietnam's advantage 10 minutes later, springing the offside trap to finish with a delightful lob from the edge of the area to finish off the Gulf Cup holders.
Japan begin their quest for a third consecutive Asian Cup title against Qatar in Hanoi on Monday in the second Group B match.
This year's tournament kicked off on Saturday and is being staged jointly by Vietnam, Malaysia, Indonesia and Thailand. The final takes place in Jakarta on July 29.
