AFP reports Greek track athlete Tassos (Anastasios) Gousis tested positive for methyltrienolone , and will be sent home.
The officials did not immediately name the athlete but Greek media later revealed that it was men's 200 metre runner Tassos Gousis, who denied any wrongdoing.
"I am innocent and my conscience is clear", Gousis told reporters. "It would be stupid for me to take a banned substance just before the Games," he added.
This event disrupts the opening day ceremonies, a bit:
The case broke on the day of the Beijing Olympics opening ceremony. In a similar twist, two Greek athletes -- sprinters Costas Kenteris and Katerina Thanou -- had also sparked the first doping controversy of the last Games in Athens by failing to appear for tests.
Greek sports officials admitted the incident but declined to name the athlete, as only the first of his two samples has tested positive.
"We have been informed that there is a positive result involving one of our athletes," Segas chairman Vassilis Sevastis told AFP.
"The athlete will be recalled and suspended pending tests on the second sample," he added, without giving further details.
Both samples -- taken from a single batch provided by the athlete at the control -- must test positive for proof of doping to be established.
The drug was methyltrienolone, a nasty anabolic steroid, popular among the Greeks.
The Hellenic Olympic Committee said in a statement that the athlete had been tested by the Greek anti-doping council (Eskan) under a scheduled check of the Greek Olympic team before its entry into the Olympic Village...
Greek media reported that the banned substance was methyltrienolone, a steroid that has already caused the elimination of most of Greece's weightlifting squad and top swimmer Yiannis Drymonakos.