American Tyler Hamilton made up for his disappointing Tour de France by surging to victory in the Olympic time trial.
Hamilton (right) won by over 18 seconds
Hamilton was only third after the first checkpoint but moved into the lead after 36km of the 48km course, coming home in 57 minutes and 31.74 seconds.
Russian veteran Viatcheslav Ekimov, the defending champion, produced another strong show to take silver in 57:50.58.
Bobby Julich completed an excellent day for the United States by claiming the bronze, with Jan Ullrich only seventh.
Hamilton, who had to abandon the Tour de France because of injury, admitted he had used that setback as inspiration for the Olympics.
"Fantastic. Unbelievable. It hasn't sunk in yet," he said.
"I gave it everything I had. I've been angry ever since crashing out of the Tour, and I took that anger out here."
Lance Armstrong, a bronze medalist four years ago, opted not to compete in Athens after his record sixth Tour de France triumph.
"I believe we are one of the best cycling countries in the world, with Lance winning the last six Tours and great results here today," added Hamilton, who finished 18th in the Olympic road race.
"It says a lot about US cycling."
Australian Michael Rogers was three seconds outside the medal positions in fourth, with Germany's Michael Rich in fifth.
Ullrich, the pre-race favourite, suffered further disappointmnent after his Tour travails, finishing over a minute and a half down in seventh.