Greek sprinter Kostas Kenteris said he was thrilled by the boos that greeted his absence from the 200m final.
Kenteris, who won gold at the distance in Sydney, pulled out of the Athens Games after missing a drugs test in unexplained circumstances.
The home crowd showed their support as jeers rang around the Olympic Stadium, delaying the final by five minutes.
"It was the best thing I have heard in years," Kenteris said. "The behaviour of the public vindicates me."
American Shawn Crawford, who claimed the gold medal in Kenteris' absence, sympathised with the crowd, saying: "I think I can understand their reaction.
"We are here in the birthplace of the Olympics, and the defending Olympic champion, for certain reasons, was not allowed to compete."
Frankie Fredericks, competing in his last Games, tried to get the booing to stop, but his pleas fell on deaf ears - prompting BBC commentator Steve Cram to call the crowd's behaviour "disgraceful".
Kenteris and training partner Katerina Thanou, who also withdrew from the Games, were backed by fellow Greek athletes.
Fani Halkia, who won the women's 400m hurdles on Wednesday, said: "People accused them without any proof. They were put against the wall, there was a firing