Bahrain's 1500m Olympic champion Rashid Ramzi was one of five athletes to appear before the International Olympic Committee's disciplinary commission in Lausanne to answer charges of doping at the Beijing Games.
He was joined at the IOC hearing by Greek walker Athanasia Tsoumeleka, Croatian middle-distance runner Vanja Perisic, and two cyclists - Italy's Davide Rebellin, silver medallist in the Olympic road race, and Stefan Schumacher of Germany.
The quintet were caught out by tests conducted in February for the new form of banned blood booster EPO-CERA.
The Morocco-born Ramzi faces being stripped of his 1500m gold, a life-ban from the Olympic Games and a minimum two-year suspension from all events.
Ramzi, who gained Bahraini citizenship in 2002 after joining the country's armed forces a year earlier, shot to fame when he won the 800m and 1500m double at the 2005 World Athletics Championships in Helsinki, becoming the first man to do so at a global event since New Zealander Peter Snell in 1964.
Ramzi won Bahrain's first ever Olympic medal when he stormed to victory in the 1500m... should he be stripped of his Olympic medal, Frenchman Mehdi Baala will step up into third place on the podium with Kenyan Asbel Kiprop and New Zealand's Nick Willis taking first and second spots.
The IOC are due to deliver their verdicts next month.
Schumacher, who tested positive in the 2008 Tour de France, is already serving a ban for doping.