The Greek football club PAOK Salonica will have to play their next three European home games behind closed doors after losing an appeal against sanctions imposed by UEFA following a riot at a match in August.
The club will also have to pay a fine of almost $240,000 and face automatic expulsion from European competition if there is a repeat incident within the next three years.
The trouble broke out before the start of PAOK's Europa League qualifying tie at home to Austrian side Rapid Vienna in August.
The Austrian club said that Molotov cocktails were among the weapons used to attack their fans as they arrived at the Toumba stadium for the match.
Video showed fans hurling a variety of firecrackers and other missiles at each other, and at one point dozens of masked fans ran onto the pitch.