The U.S. boxing team sucked on sour grapes after being left with just one gold medal prospect in the Olympic boxing tournament on Friday.

While middleweight Andre Dirrell accepted he had been out-pointed fair and square in the semi-finals by Kazakh World champion Gennadiy Golovkin, a view shared by ringside observers, U.S. assistant coach Anthony Bradley saw otherwise.

"We lost the bout but I felt we won it," he said.

"It's amateur boxing. You've all seen it for yourselves so I'll let you judge what you think about it," he told a news conference. "We lost points before we stepped into the ring, if you ask me.

"There's just certain countries that you compete against in this sport where right off the bat you realise they don't have to really score, just to throw the punches and if they touch you they get points for no reason at all.

"And people wonder what's wrong with amateur boxing ... it's about humanity and sportsmanship which is not here."

Bradley doubted whether there would be an appeal, although he wished he could.

"Throughout the whole tournament you see the same thing and over and over people talk about doing the right thing and it stops right here," he said.

"You wonder why people talk about putting amateur boxing out of the next Olympics.

"In some of these bouts you've got certain judges and certain officials appointed to certain countries," said Bradley. "You can see it for yourselves but I'm not going to name names because the damage is already done."

Dirrell's defeat left the U.S. team with just light-heavyweight Andre Ward standing between them and another barren Olympics.

In Sydney four years ago the once-mighty Americans got no golds for the first time since 1948 and they will take just two medals home from Athens this time with the beaten semi-finalists assured of bronze.

Dirrell said he would turn professional, a recurring problem for the U.S. team whose brightest prospects do not hang around long as amateurs before being signed up to the paid ranks.

The 21-year-old from Flint, Michigan, said he was happy to at least have a medal.

"I accept the bronze and take it back to the USA with pride," he said. "He fought smartly and I can't take anything away from him.

"The refs do what they're told and they're scoring all the same, I believe," he added.