Thai League champions Buriram United lost 2-1 at FC Seoul in their penultimate game of the AFC Champions League yesterday.
Buriram's Chaowat Veerachat, in white, vies with FC Seoul's Yojiro Takahagi.
It was the Thunder Castle's fifth straight defeat in Group F of the current campaign.
The hosts sealed top spot of the group and a place in the last-16 round.
First-half headers from Dejan Damjanovic and Park Yong-Woo put the 2013 runners-up on the way to their fourth win in five games while the Thai champions are still searching for their first points of the campaign.
The visitors did get their first goal of the tournament, however, thanks to a second-half penalty from Venezuela defender Andres Tunez.
Having been eliminated, Buriram fielded several young players for them to gain experience.
But the second-string side did well to escape with a narrow defeat.
Buriram had conceded 14 goals, including six at home to FC Seoul, in their previous four matches.
Seoul took control of the game from the start and almost went ahead in spectacular fashion in the third minute.
Damjanovic headed a Go Yo-Han cross back across the six-yard box for Adriano to send a perfect overhead kick that Buriram goalkeeper Siwarak Tedsungnoen did well to push behind for a corner.
The home team went on to take a 2-0 lead at half-time.
Out of nowhere Buriram got back in the game with their first goal of the tournament midway through the second half.
Sittichok Kannoo was brought down just inside the area and Venezuela international Tunez stroked the ball coolly into the corner.
The goal stung FC Seoul but the K-League side could not restore their two-goal advantage with Park Chu-Young and Park Yong-Woo coming close.
Buriram rarely threatened to get an equaliser and FC Seoul took the three points that confirmed them as the group winners and, with it, their place in the last 16.
In the other Group F match, China's Shandong Luneng drew 1-1 with Japan's Sanfrecce Hiroshima.