Thailand beat 10-man Vietnam 1-0 on Sunday night in a World Cup qualifying match for the 2018 finals in Russia.
Substitute Pokklaw A-Nan scored the only goal in the 80th minute at the Rajamangala National Stadium.
Vietnam's Minh Chau Nguyen was sent off in the 71st minute for a second yellow card and Thailand finally struck with 10 minutes to go when Pokklaw shot home off a pass from Teerasil Dangda.
The two teams are in Group F which also includes Iraq, Indonesia and Taiwan.
The match took place earlier than other qualifiers as several players from both sides are due to play in the SEA Games in Singapore, starting June 5.