The emphatic win lifted coach Kim Sang Sik's side to seven points from three matches, ahead of Singapore on goal difference, while Indonesia slipped to third with six points.
Vietnam, the defending champions, stunned the home crowd by racing into a two-goal lead inside the opening 14 minutes, displaying a level of confidence and attacking fluency that contrasted sharply with their earlier draw against Singapore.
The visitors repeatedly targeted Indonesia's vulnerable left flank, where the partnership between Rizky Ridho and Eliano Reijnders struggled to contain the pace and movement of Hai Nguyen Long and Nguyen Van Vi.
That approach paid off almost immediately.
Vietnam opened the scoring in the sixth minute after forcing a turnover high up the pitch. Van Vi combined neatly with Nguyen Hoang Duc before bursting into the penalty area and firing a powerful shot from a tight angle past goalkeeper Nadeo Argawinata.
Eight minutes later, Vietnam doubled their advantage. A long pass from Thanh Long released Hai Long, who sprinted clear of the Indonesian defense before calmly beating Argawinata with a composed finish at the near post.
Holding a 2-0 lead, Vietnam settled into a disciplined defensive shape while remaining dangerous on the counterattack. Kim's men controlled possession when needed and created several more opportunities before half-time that could have extended their advantage.
Indonesia increased the pressure after the break in an attempt to stage a comeback, but Vietnam's backline remained composed. Center-back Bui Hoang Viet Anh produced a series of crucial interceptions and clearances to frustrate the hosts.
Kim introduced naturalized players Nguyen Xuan Son and Hoang Hen in the 63rd minute, and the substitutions quickly paid dividends.
In the 71st minute, Hoang Duc threaded a perfectly weighted through ball into Xuan Son's path. The forward accelerated beyond the Indonesian defense before coolly finishing past Argawinata to make it 3-0 and effectively seal the victory.
Indonesia pushed forward in the closing stages but lacked composure in the final third and found little space against Vietnam's well-organized defense.
The Vietnamese could have added further goals, with Hoang Hen and Dinh Bac both missing promising chances late in the match.
The convincing result leaves Vietnam in pole position to qualify for the knockout stage.
In the final round of Group A matches, Vietnam will face Cambodia, while Indonesia take on Singapore in a crucial encounter that could determine the remaining semifinal berth.
Thailand and Malaysia are leading Group B.
The ASEAN Hyundai Cup 2026 is Southeast Asia's premier men's international football tournament, organized by the ASEAN Football Federation (AFF). Formerly known as the AFF Championship and later the ASEAN Mitsubishi Electric Cup, the competition is sponsored by Hyundai for the 2026 edition.
Thailand are the tournament's most successful nation, while Vietnam are among the region's traditional powerhouses, having won ASEAN titles in 2008, 2018, and 2024.
Yen Viet / Tuoi Tre News