Heavyweight Devin Vargas dropped a 36-27 decision to Viktar Zuyev of Belarus, the latest of a string of disappointing losses for the U.S. team.
"I knew I had to knock him out or get him disqualified for holding me to win," Vargas said. "I was just trying to knock him out."
Vargas, who would have been ensured at least a bronze medal if he won, was holding his own until he twisted his left knee, which had been bothering him since the team arrived in Athens.
After the round ended, Coach Basheer Abdullah told Vargas he had no choice but to move forward and trade punches with Zuyev. The problem was, Vargas had spent the last three months learning to do just the opposite: box and move.
"I know I could have bounced on my toes and won if my knee wasn't hurt," he said. "My coach told me to just go forward and I hadn't practiced going forward."
Vargas ended up taking two standing eight counts -- one for a low blow -- and Zuyev picked him apart with punches to the head.
Vargas rocked Zuyev with a right hand early in the second round. But as the American grew increasingly desperate, Zuyev managed to avoid most of his punches.
The loss left only three U.S. fighters still in medal contention -- middleweight Andre Dirrell, super heavyweight Jason Estrada and light heavyweight Andre Ward.