Melbourne City have slipped from the top of their Asian Champions League group after falling to a 1-0 home defeat against Thai side Buriram United.
Undefeated in their group heading into Wednesday's contest at AAMI Park, success would have guaranteed City at least a three-point buffer atop group H with two games to go before the knockout stages.
Instead, their defeat, combined with Ventforet Kofu's 4-1 win over Chinese outfit Zhejiang in another Wednesday kickoff, has enabled the Japanese side to go top on goals scored, as well as leaving the A-League Men premiers just a point above third-placed Buriram.
Only group winners are guaranteed progression, with the three best second-placed finishers from the East region to join them in the knockout stages.
City had downed Buriram 2-0 in Thailand a fortnight ago but had a new face in the dugout for the return leg with Aurelio Vidmar taking charge of his second game after Rado Vidosic was sacked last week following a horror start to the ALM season.
But while Vidmar had won in his first game against Sydney FC last Friday, he could only watch on in dismay as his side failed to penetrate the 'Thunder Castle' defence before being made to pay when Goran Causic fired home an 86th-minute penalty after a handball by Aziz Behich.
"We had a fair bit of the game but we really lacked a little bit of an edge in the front," said Vidmar.
"I don't think we deserved to lose.
"A draw would have been a fair result but that's the way it is, we've hit a bit of a speed bump and gotta get on with it."
City twice had goals disallowed for offside in the opening stanza, the first coming in the 29th minute when Jamie Maclaren had a close-range finish ruled out and the second in the 41st when Tolgay Arslan followed up a saved effort from his skipper.
But despite seeing less of the ball throughout the contest, Buriram, led by former Newcastle Jets coach Arthur Papas, adjusted at the interval and clamped down in the second 45.
They then finished strongly and grabbed a winner.
Buriram players and staff jubilantly celebrated with a sizeable contingent of supporters at fulltime, while the family of Mebourne-born Papas were in the stands watching on.
"The reaction at the end tells you everything," Papas said.
"It's a pretty special night for this club."
