South Korea's Suwon Bluewings called Thursday for Qatari team Al Sadd to be punished after their AFC Champions League semi-final was marred by an ugly brawl.
Wednesday night's match at Suwon World Cup Stadium south of Seoul was temporarily halted as both teams traded punches.
A tepid encounter exploded late in the second half after Al Sadd's Mamadou Niang raced through for his breakaway second goal while much of Suwon's team were tending to an injured player.
Players then remonstrated with the referee and as the game was about to get underway again a fan invaded the pitch, sparking a pushing and shoving match.
It deteriorated into chaotic scenes as players and staff were drawn into fighting which blighted one of Asia's biggest club games.
Suwon lost the game 2-0 and now face a daunting task in the second leg of the semi-final next Wednesday to reach the final.
"The opposition scored an ungentlemanly goal but there's nothing we can do about it," Suwon coach Yoon Sung-Hyo said late Wednesday.
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"We now face a difficult task for the second leg but we will prepare as well as we can and do our best."
The South Korean club admitted Thursday it failed to provide adequate security at the ground.
But it denounced a Qatari player for allegedly hitting the fan who invaded the pitch, calling it a "very rare" action that deserves tough punishment.
The fan jumped from the stands to argue with Al Sadd goalkeeper Mohamed Saqr Ahmed. A Qatari teammate later slapped the fan in the head before grabbing him by the throat, local media reported.
"We'll take responsibility for the lack of security, but I expect the opponents to get far heavier punishment for the ungentlemanly act and assaulting the fan," Suwon team spokesman Choi Won-Chang told AFP.
"We expect the AFC to carefully review such a rare action against a fan."
An Asian Football Confederation official who watched the match took statements from both teams.
In Kuala Lumpur, an AFC official said the confederation's legal and referee departments were reviewing footage of the game and other material.
Their report would be submitted to the AFC's disciplinary committee, which would decide what action to take against the teams, he told AFP on condition of anonymity.
"We are aware that an urgent decision is needed as there will be a semi-final next week," the official said. "So there will definitely be a decision before next week."