Flyweight Marlen Esparza and middleweight Claressa Shields also clinched the U.S. team's first two boxing medals in London. Esparza patiently outboxed Venezuela's Karlha Magliocco, and the 17-year-old Shields closed furiously in an 18-14 win over Swedish veteran Anna Laurell.
The Americans also emerged in awe of the atmosphere in this Olympic debut.
"I had to keep myself calm out there," said Shields, who could still hear instructions from her personal coach, Jason Crutchfield, shouted from the stands. "I didn't want to be overanxious, but it was kind of like, 'Wow.' "
Esparza, the 23-year-old Cover Girl model from Houston, noted, "I thought the crowd was going to freak me out a lot more than it did. I've never fought in front of something like that."
Volleyball. David McKienzie scored 17 points and the defending champion U.S. men's volleyball team clinched a top tournament seed with a win over Tunisia, setting up a quarterfinal against Italy on Wednesday.
Beach volleyball. Jake Gibb and Sean Rosenthal left Beijing with a fifth-place finish and a good feeling about how they performed in their first Olympic beach volleyball tournament.
When they were eliminated from the London Games, they didn't have the consolation of exceeding their expectations.
"It's 100 times worse," Gibb said after the Americans squandered a victory in the first set to lose, 19-21, 21-18, 15-11, to Latvia in the quarterfinals and match their 2008 finish. "That was our first time and we lost to the defending gold medalists. I'm not saying we were supposed to lose that time or win this time, but it's different.
"I really felt like we were going to win a medal."
The United States is already guaranteed a medal in the women's bracket, with two-time gold medalists Kerri Walsh Jennings and Misty May-Treanor in the semifinals along with April Ross and Jennifer Kessy. So the nation that invented volleyball and brought it to the beach will not go home empty-handed.
Water polo. After a quick start, U.S. men's water polo team is slowing down at the wrong time.
Norbert Hosnyanszky scored three times and defending champion Hungary beat the U.S., 11-6, to close out the preliminary stage. The defeat - the Americans' second straight - exposed a simple problem that has turned urgent for the U.S. with a quarterfinal matchup against undefeated Croatia looming on Wednesday.
"Look, it's defense, that's it," captain Tony Azevedo said. "Six goals is not enough, but that's fine. But when on defense you can't make a stop, you can't expect to win. Defense is the part of the game that's really the easiest to change. It's heart and it's passion, and right now we're not playing with it, and I honestly can't tell you why."
With both teams already into the quarterfinals, the only thing on the line for the U.S. and Hungary in Monday's game was a better seed for the knockout stage.
Equestrian. Led by a rider who returned to the sport after breaking his neck in a competition fall, Britain won its first Olympic show-jumping gold medal in 60 years.
Three members of Britain's four-man team - Nick Skelton, Ben Maher and Peter Charles - rode clear rounds in a jumpoff to give the host team victory over the Netherlands. Saudi Arabia, a relative newcomer to the sport, was a surprising third.
Skelton, 54, fractured his neck in 2000 but returned to riding two years later.
"After I broke my neck, my goal was to get back to Athens in 2004 and then to get to here," Skeleton said. "When you have a horse as good as Big Star, you look forward to getting up every day and riding him."
Competing in his fifth Olympics, Skelton said he was more nervous watching his teammates than riding himself.