The highly anticipated Group B encounter at Si Jalak Harupat Stadium in Bandung, Indonesia, on September 29 swung Thailand’s way early when Sarach Yooyen struck from distance in the 10th minute.

Vietnam thought they had equalized through Tai Loc in the 37th minute, but the goal was ruled out for offside following a VAR review.

Kim Sang Sik’s side pushed forward after the break and created several opportunities, but Thailand’s disciplined defense held firm before Chaiyaphon Otton broke through in stoppage time to seal the 2-0 victory.

The result ended Vietnam’s 27-game unbeaten streak under Kim and secured Thailand top spot in Group B with six points, sending them into the final.

For Vietnam, the defeat was more than a bad result. It highlighted problems in personnel, tactics and finishing at a crucial stage of the tournament.

Kim’s tactical gamble fails to pay off

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Vietnam struggled to make Kim Sang Sik’s tactical changes work effectively. Photo: V.A

Kim made four changes to the starting lineup from Vietnam’s win over the Philippines and switched his formation from 3-4-3 to 5-3-2.

With Xuan Son unavailable through injury, Kim opted for two forwards rather than a single center forward, deploying Dinh Bac alongside Tai Loc.

There were significant changes elsewhere as well.

Cao Pendant Quang Vinh was moved into central midfield, a role requiring him to cover considerable ground while contributing both defensively and in building attacks. Minh Khoa was also instructed to operate further forward to provide greater support for the two strikers.

In defense, Phan Tuan Tai was used on the left flank while Ngoc Bao played at center back.

The setup suggested Kim wanted Vietnam to tighten the middle of the pitch while attempting to surprise Thailand with personnel choices different from those used previously.

The plan, however, produced little attacking cohesion.

Dinh Bac and Tai Loc struggled to establish an effective partnership and were frequently contained by Thailand’s defense. With neither forward consistently able to retain possession, the limited supply from deeper areas rarely found a reliable target.

That also prevented Vietnam’s midfield from pushing higher up the pitch. The team repeatedly moved the ball forward only to lose possession quickly instead of building sustained attacks.

Quang Vinh’s positioning proved particularly problematic.

The player is more effective on the left, where he can exploit his speed, dribbling and ability to move up and down the flank. In central midfield, those strengths were largely neutralized, while he repeatedly occupied similar spaces to his teammates.

When Quang Vinh returned to his more familiar role in the second half, his performance immediately improved, reinforcing questions over the decision to start him centrally.

Kim is entitled to experiment, and such trials may even be necessary if Vietnam are to build greater squad depth and reduce their dependence on a handful of key players.

But the timing proved costly. The Thailand match was crucial to Vietnam’s hopes of reaching the final, while their rivals arrived determined to respond to a series of recent defeats against the Vietnamese.

Thailand punish Vietnam’s mistakes

Thailand did not need to dominate possession to control the match.

With players including Chanathip Songkrasin, Nicholas Mickelson, Manuel Bihr and Sarach, Thailand looked more composed, structured and clinical.

Sarach’s opening goal came after Vietnam failed to clear a cross effectively, allowing the midfielder to fire home from outside the penalty area.

Vietnam responded and enjoyed periods of pressure. Tai Loc’s disallowed goal offered their best moment of the first half, but Thailand went into the break 1-0 ahead.

Kim made three substitutions before the second half, introducing Hoang Duc, Hoang Hen and Minh Hoang for Minh Khoa, Tuan Tai and Tai Loc. Dinh Bac also handed the captain’s armband to Hoang Duc.

The changes helped Vietnam improve.

Hoang Duc came close to equalizing in the 58th minute after Hoang Hen played him through, but goalkeeper Saranon Anuin reacted in time to deny him.

Vietnam continued to press, but Thailand defended with numbers and restricted their opponents’ routes to goal.

At the other end, goalkeeper Patrik Le Giang made an excellent save from Peeradol Chamrasamee’s close-range header in the 80th minute.

Vietnam committed more players forward in search of an equalizer in the closing stages, leaving space behind.

Thailand eventually exploited it in stoppage time, with Otton beating the offside trap and finishing past Le Giang to make it 2-0.

Thailand deserved the victory, expert says

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Vietnam produced a below-par performance against Thailand. Photo: V.A

Vietnamese football commentator Quang Huy said Thailand deserved the result, arguing that the balance of strength between the two teams had shifted compared with previous tournaments.

He said Thailand had assembled a stronger squad, while Vietnam were missing important players and had become significantly weaker compared with the ASEAN Cup.

Chanathip, despite no longer being at his peak, remained crucial to Thailand’s attacking structure and ability to connect their play, Quang Huy said.

Thailand attacked less frequently but did so with greater clarity, while their ability to control the game after taking the lead demonstrated their experience.

Vietnam, by contrast, were without several important players.

Quang Huy highlighted the absence of Xuan Son in particular, describing him as still the best center forward available to Vietnam despite the serious injury he had previously suffered.

Dinh Bac, he said, is naturally more comfortable playing wide and remains inexperienced when used as a central striker.

The commentator also warned against overestimating Vietnam’s position in Southeast Asian football as Thailand, Indonesia, Malaysia and the Philippines continue strengthening their squads.

For Quang Huy, Thailand’s quality was ultimately the key factor.

Kim had set Vietnam up to defend, counterattack and transition quickly, but conceding after only 10 minutes disrupted that plan and forced his side to push forward earlier than intended.

Kim takes responsibility

Kim accepted responsibility after the defeat and apologized to Vietnamese supporters.

“I want to apologize to the fans. Our players gave everything in this match,” he said. “I prepared different tactical plans for the two halves, but the final result was not what we wanted. Although we lost, the tournament is not over. The team will continue preparing for the upcoming match against Pakistan.”

Kim acknowledged that Vietnam had struggled particularly in midfield during the first half.

After personnel and tactical changes, he believed the team performed better in the second half and increased the pressure on Thailand.

But Vietnam could not convert their opportunities.

“As head coach, this result is my responsibility,” Kim said.

He also acknowledged the impact of Xuan Son’s absence, saying Vietnam might have scored had the striker been available, although he stressed that this remained hypothetical.

Kim said Thailand had brought a stronger squad to the FIFA ASEAN Cup than they had fielded at the ASEAN Cup, while Vietnam had undergone numerous changes and had not prepared as well as their opponents.

Players admit missed chances proved costly

Hoang Duc, who entered at halftime, said Vietnam had created opportunities but failed to convert them.

“Vietnam were unlucky. We had many chances but couldn't score. In football, there are wins and losses, so we have to accept it,” he said.

Hoang Duc said he had completed only two full training sessions before the match and was not yet fully accustomed to playing at high intensity.

He also praised Chanathip as one of Southeast Asia’s leading players, saying the Thai captain’s presence provided significant motivation and confidence to his teammates.

Dinh Bac was equally disappointed but said the defeat should become a lesson for Vietnam.

“We tried hard and created many dangerous chances. But in football, when you cannot score, you pay the price by conceding,” he said. “No team can remain unbeaten forever.”

Vietnam’s match report showed the team had continued to press deep into the second half but struggled to break through Thailand’s compact defense.

Thailand celebrate ending Vietnam’s unbeaten streak

For Thailand, the result carried significance beyond three points.

Chanathip said he had personally gone around five years without beating Vietnam and had watched their regional rivals improve substantially during that period.

Vietnam had gone 27 consecutive matches unbeaten before the defeat, making the victory particularly satisfying, he said.

Thailand coach Anthony Hudson also highlighted the importance of overcoming an opponent his team had struggled to beat in recent years.

He described the current Thai squad as the best generation of players he had worked with in Thai football and said having a strong lineup gave him confidence his team could finally overcome Vietnam.

Thai media celebrated the result, with Siam Sport highlighting both the final berth and Thailand’s rise to No. 90 in the FIFA rankings, while reporting that Vietnam had slipped two places to No. 99.

Indonesia’s Kompas also focused on the end of Vietnam’s unbeaten streak and Thailand’s superior efficiency.

Vietnam recorded more shots, but Thailand generated more efforts on target and made better use of their opportunities.

Thailand’s two goals came from Sarach in the 10th minute and Otton in stoppage time, while Vietnam’s only effort to reach the net was Tai Loc’s disallowed first-half strike.

A defeat that exposes what Vietnam must fix

The 2-0 loss was not simply the result of Thailand being stronger.

Vietnam also made the task more difficult through tactical and personnel choices that failed to work as intended and required correction after the match had already turned against them.

The defeat ended a long unbeaten run that had at times helped conceal weaknesses behind positive results.

Facing a strong Thailand side at close to full strength brought those shortcomings into sharper focus.

Vietnam were missing key players, but their inability to finish opportunities, uncertainty in several unfamiliar positions and defensive mistakes all contributed to the defeat.

Kim’s experimentation may ultimately prove useful as Vietnam build toward bigger objectives, particularly the 2027 AFC Asian Cup. But against Thailand, the calculations did not produce the desired result.

Vietnam have also suffered another personnel setback, with striker Gia Hung leaving the squad and returning home for family reasons. Following Xuan Son’s injury, Kim now has only Dinh Bac, Tai Loc and Minh Hoang available as strikers.

The team returned to training on September 30 before traveling from Bandung to Jakarta for their match against Pakistan on October 2.

With the title now out of reach, Vietnam must regroup, learn from the defeat and use their remaining matches to test personnel and build a stronger core for the challenges ahead.

Duy Nguyen - Dai Nam - Ngoc Huy