The U.S. women's soccer team defeated Canada 4-3 in an extra-time thriller that is bound for the history books.
Despite trailing the Canadians in the first half, the U.S. team held on and forced the game into extra time, where several failed attempts on both sides culminated in a last-minute header by Alex Morgan that sailed narrowly over the hand of Canadian goalkeeper Erin McLeod.
The United States will contend for a gold medal Thursday against the Japanese, who defeated the French team 2-1 in the other semifinal match.
The gold-medal match will be a chance for revenge for the Americans, just one year after Japan beat them 3-1 in the 2011 World Cup final.
"This is what we've been working toward ever since we lost to Japan," said U.S. forward Abby Wambach after the semifinal win.
The three goals Canada scored were the first the U.S. team had allowed in London, following shutouts of North Korea and New Zealand.
Both sides came within inches of winning the match just minutes before extra time began.
At the 85th minute, Abby Wambach, who delivered her team's only goal against North Korea, fired wide of the goal, missing a chance to seal a U.S. victory. Five minutes later, U.S. goalkeeper Hope Solo saved what looked like a winning shot by Canadian Sophie Schmidt.
In extra time, Heather O'Reilly missed an open net after McLeod failed to stop a cross. Wambach headed the ball off the crossbar in the 119th minute, just barely missing the game-winner.
The game seemed bound for penalty kicks, a first for Olympics women's soccer, when Morgan's header found just enough space between McLeod's glove and the crossbar.
"It was a crazy battle," Morgan said immediately after the match. After 120 minutes of soccer, she said, the Americans will now enter a period of "recovery" as they prepare for their rematch against Japan.
Following the performance last Thursday night that gave American gymnast Gabby Douglas the first all-around gymnastics gold medal ever awarded to an African-American, Douglas placed a disappointing eighth in the uneven bars, expected to be her best event.
Reigning gold-medalist Elizabeth Tweedle of Britain won the bronze in the event, while Russian Aliya Mustafina won the gold.
In water polo, the U.S. men's team fell to defending champion Hungary 11 to 6 in a semifinal match that drowned the gold-medal ambitions the Americans stoked after winning silver in Beijing in 2008.
American runner Allyson Felix easily won the heat in the 200 meters, the event she calls her "baby." Felix withdrew herself from contention for the 100 meters after she placed in a dead heat for third with teammate Carmelita Jeter. The two were scheduled to compete in a runoff race, but Felix, who felt she had earned her spot on the team the first time, withdrew at the last minute.
Along with two other American hurdlers, Lolo Jones qualified for the semifinal in this morning's heats in the 100-meter hurdle event. Jones gained celebrity in 2008 after she appeared poised for a gold in the 100-meter final in Beijing only to fail to clear the second-to-last hurdle in the race.
Sally Pearson of Australia set the fastest 100-meter time Monday.
Americans Nick Symmonds and Duane Solomon qualified for the semifinals in the men's 800 meters, while Khadevis Robinson was eliminated from the pack.
In the men's 400-meter final, American Angelo Taylor was aiming for his third gold medal in the event, but he finished fifth.
Morgan Uceny easily advanced to the semifinals in the women's 1,500, but teammate Jenny Simpson only narrowly made it into the first six. American Shannon Rowbury also qualified for the event.