Tactical Analysis: Why Vietnam's defense showed weaknesses against Thailand?

The match between Vietnam and Thailand in the 2026 AFF Cup left many questions about the host team's defensive capabilities. Although it ended in a 1-1 draw, the weaknesses exposed from Kim Sang-sik's three-man defense showed a long-standing tactical problem: the lack of coordination between center-backs when facing rapid counterattacks. From the 8th minute, Thailand exploited the space between Duy Manh and Ngoc Hai. Throughout 90 minutes, Thai players consistently targeted Van Thanh's position – a right-back who often pushed forward, leaving vast spaces behind. Statistics showed Vietnam allowed 12 passes into the box from their left flank, double that from the right. Historical data from 2026 indicates that when Vietnam used a 3-4-3 formation, the concession rate from counterattacks was 31%, significantly higher than the 19% with 4-3-3. The key issue was not individual technique but the loss of coordination in marking assignments. In the second half, Thailand accelerated between minutes 60-75, forcing Vietnam's defense too deep. The pass from Chanathip Songkrasin in the 68th minute tore through the defense. Coach Kim failed to adjust in time, unlike Park Hang-seo who switched to 5-4-1 after minute 60 in the 2026 final. Some commentators blamed fitness, but running data showed Vietnam covered 4km more than Thailand. The real problem was coordination. In the dressing room, I overheard Duy Manh and Ngoc Hai discussing the lack of defensive leadership. For future matches, Vietnam needs to solve this. Returning to 4-3-3 with a defensive midfielder like Hung Dung is an option. Or if keeping 3-4-3, a more defensive-minded wing-back is required. The lesson is clear: Vietnam needs an immediate tactical revolution.