Thailand went down to Turkmenistan 3-1 in a key qualification match for the 2026 AFC Asian Cup in Ashgabat on Tuesday night.
The victory saw hosts Turkmenistan open up a three-point lead at the top of the Group D standings, with a maximum of six points from two games.
Thailand are second with three points while Sri Lanka, who defeated Taiwan 3-1 in Colombo on Tuesday, are third with three as well.
Only the winners of the six groups in the qualifying tournament will join the 18 countries who have already qualified for the finals in Saudi Arabia.
The defeat in Ashgabat was pivotal as it came against a team seen as the War Elephants' main competition for the top spot in the group.
Turkmenistan got off to a perfect start, taking the lead after only 40 seconds through Mikhail Titov, who struck the ball past Thailand goalkeeper Patiwat Khammai.
Thailand came close to levelling the score in the 11th minute but centre-back Elias Dolah's header from inside the area went over the bar.
The War Elephants equalised in the 35th minute after forward Supachai Chaided rose highest to nod home from a set-piece.
However, Thailand's joy was short-lived as the hosts regained the advantage two minutes later through Shanazar Tirkishov.
Turkmenistan put the match beyond Thailand's reach in the 66th minute after the visitors' defence failed to clear a corner and Mekan Saparov pounced on a loose ball to slot home.
"I think Turkmenistan had a clear method of playing. They have about 8-9 players that come from the same club so their understanding of the game was good. This created problems for us," said Thailand coach Masatada Ishii during a post-match press conference.
"It is true that we conceded the first goal very quickly but we played well during the first half. We just have to accept that Turkmenistan's defence was strong, so we couldn't score," he added.
Thailand captain Chanathip Songkrasin admitted the team did not play well but also pointed out that the artificial pitch at the Ashgabat Stadium did not help Thailand's cause on the night.
"Of course, the artificial pitch was a problem for our team but I have to say that we did not play well today," he said.
In Colombo, Sri Lanka got three goals from Adhavan Rajamohan (49th minute), Dillon de Silva (53rd) and Ahmed Waseem Razeek (59th) while Taiwan pulled one back from Huang Wei-chieh (70th).
Thailand, who beat Sri Lanka in their first game in March, will have back-to-back qualifiers against Taiwan in October, with the first game at home on Oct 9 and the second match away five days later.
Ishii's men will now turn their focus to the 51st King's Cup preparation. The tournament will take place in September.