Thailand lost 2-0 to Japan in the War Elephants' first match at home in their bid to go to the 2018 World Cup.
The two teams needed a point after suffering their first loss in Group B of Asia's final phase of qualifiers for the World Cup in Russia.
Thailand were edged 1-0 by Saudi Arabia in Riyadh and Japan succumbed to a 2-1 home defeat to the United Arab Emirates on Sept 1.
Japan took control of the game from the start at the packed Rajamangala National Stadium. And a header by Genki Haraguchi from Hiroki Sakai's cross after 15 minutes helped the visitor break the deadlock and gave the visitors a maximum three points.
The second goal from Asano Takuma 15 minutes from time gave the visitors a comfortable lead to get their first three points in the campaign.