The 2-0 victory at Rizal Memorial Stadium in Manila kept alive the Thai hopes of making it to the semi-finals from Group B of the U23 tournament at the SEA Games in the Philippines.
In the other Group B matches on Tuesday, Vietnam's winning streak continued as they edged Singapore 1-0 with a late goal and Indonesia, as expected, trounced Brunei 8-0.
Vietnam remained the top-ranked side in the group table with 12 points and now hold a three-point advantage over both Thailand and Indonesia.
With Indonesia heavy favourites to beat Laos in their last group game tomorrow (Dec 5), three-time defending champions Thailand must get the better of Vietnam on the same day to stake a claim for a place in the semi-finals.
The top two teams from each group will qualify for the knockout stages with the semi-finals scheduled for Saturday (Dec 7) and the third-place play-off and final to be played on Dec 10.
Thailand coach Akira Nishino admitted that Laos' defensive mindset and the rain in Manila made things difficult for the Thais.
"It was a difficult game for us. The condition of the pitch made it very difficult for us to get going, especially in the first half," said Nishino.
"In the second half, we changed our tactics and sent in some fresh players.
"It is a tough tournament and it is difficult to have players ready and fit for every match."
Referring to the promised goal-fest that didn't materialise on Tuesday, Nishino said, "The way things were, it was never possible to score many goals.
"But we won the match and it gives the players a lot of confidence ahead of our match with Vietnam, which is very important for us.
"Vietnam is a strong team but we have studied their style and planned our tactics accordingly. We also have to check on the fitness of the players."
The match seemed to be heading for a goalless draw before Buriram forward Suphanat ended the stalemate with a lob in the 89th minute. He picked up his second in the injury time.