Chile's Fernando Gonzalez dumped second seed Andy Roddick out of the Olympic tennis tournament in the third round.
The world number 20, who had only won one of their three previous encounters, took just one hour and 12 minutes to seal a 6-4 6-4 victory.
Roddick looked off form in Athens and failed to convert four break points in the decisive game of the match.
"I'm gutted right now," said the world number two. "It's not every day we get to play this, you can't say next year."
Gonzalez quickly grabbed a break in the third game of the match as Roddick missed a forehand and served up two double-faults.
The 16th seed then broke Roddick to love to go 5-4 up in the second and virtually ensure his place in the quarter-finals.
Roddick followed world number one Roger Federer out of the Games and will now focus on defending his title at the US Open, which begins on 30 August.
Taylor Dent gave some hope to the American camp as he beat Croatia's Ivan Ljubicic 6-4 6-4 to progress.