And the rest of the world took advantage, turning the London Games into a sea of athletic parity.
The Dominican Republic not only won its fifth Olympic medal in history, it won its sixth. Saudi Arabia collected its third medal of all time and Kuwait won its second.
Never before had either Cyprus or Grenada won an Olympic medal, but now both of them have. Grenada's medal was a gold one, won by 400-meter world champion Kirani James in an event traditionally dominated by the Americans but one in which no runner from the United States could be found Monday.
It was only the second time in Olympic history no U.S. runner qualified for the finals of the 400, the other time coming when much of the world, including the United States, boycotted the Moscow Games in 1980.
Nine countries that had not yet won a medal in London did so Monday, including Puerto Rico, Estonia, Turkey and Trinidad and Tobago.
Tunisia won its second medal of these Olympics. So did Egypt and Georgia. Iran won both its second and third.
In all, 32 countries shared Monday's medals. The only country to win more than three was Russia, which hogged seven.
Nine medals were handed out in gymnastics and seven countries divided them up. There were 11 nations represented among the 12 medal winners in Greco-Roman wrestling.
The lone gold medal claimed by the United States came from Jennifer Suhr in the pole vault. She surprised two-time defending Olympic champion Elena Isinbaeva of Russia, who finished third behind silver medalist Yarisley Silva of Cuba.
Michael Tinsley won a silver for the Americans in the 400-meter hurdles, where 2004 Olympic champion Felix Sanchez of the Dominican Republic managed another triumph.
There was only one other medal for the Americans all day and Matt Emmons almost let it get away, something he has done before in one of the more bizarre careers in Olympic history.
Emmons finished third in the 50-meter rifle, three-position event, where he was in a solid second place heading into his final shot.
Instead of registering something in the neighborhood of 10 on the shot, which he would have been expected to do, he managed only a 7.6. He hung onto the bronze medal by three-tenths of a point.
Eight years ago he had the gold medal all but wrapped up in the event, but in one of the most famous stories in Olympic history he shot at the wrong target. He dropped from first to eighth. It was after that competition, however, that he met his wife-to-be -- a world class shooter from the Czech Republic who has three Olympic medals to her credit.
Emmons also had the gold in the bag in 2008, but as he positioned his rifle for the final shot it fired before he was ready. He fell from first to fourth place on that occasion.
Although the United States did not pick up many medals Monday, the American women's soccer team put themselves in position for a gold one with a 4-3 win in overtime over Canada in the semifinals.
A controversial penalty kick by Abby Wambach allowed the Americans to tie it late in regulation. The Canadian goalkeeper was ruled to have held the ball too long before getting rid of it, allowing the Americans a free kick. On that kick a handball was called in the penalty area, setting up Wambach's game-tying effort.
Alex Morgan then gave the United States the win with 30 seconds left in the second overtime by lofting a header over the goalie and under the crossbar.
In the gold medal game Wednesday, the Americans will have extra motivation. Not only will an Olympic title be at stake, which would be their third, they will be seeking revenge against Japan for a loss in last year's World Cup final.