The chaos stunned a crowd of about 5,000 at the Athens Olympic Arena, as players from the two teams exchanged punches and kicks. A few spectators entered the fray and were quickly shoved out of the arena. Greece was leading 74-73 when the match was abandoned.
Both teams qualified for the world championships in Turkey beginning Aug. 28.
The trouble began when Greek forward Antonis Fotsis had moved threateningly toward Serb guard Milos Teodosic after a hard foul, and Nenad Krstic appeared to grab Fotsis by the throat.
Krstic then threw a chair at Greek center Sofoklis Schortsanitis, who was pursuing him, and it hit Greek center Yannis Bouroussis in the head. Blood trickled from his wound.
The players exited toward the locker rooms and fought in the tunnel leading from the arena before eventually being separated. The fighting happened about six minutes after Serb coach Dusan Ivkovic was ejected with two technical fouls for arguing heatedly with a referee.
Earlier Thursday, veteran guard Jaka Lakovic scored 19 points to lead Slovenia (1-2) to its first victory, 86-71 over Canada. Guard Jevohn Shepherd was Canada's top scorer with 13.
Slovenia's lead topped 20 points several times, and the Canadians — surprise 62-58 winners over Serbia on Wednesday — could close within only 13 in the final period.