Kerri Walsh Jennings suffered the first match loss of her Olympic career on Aug. 16, when she and beach volleyball partner April Ross fell to Brazil’s Agatha Bednarczuk and Barbara Seixas in straight sets.
The loss was particularly painful for Walsh Jennings, who was in search of a record-breaking fourth straight gold medal in her storied Olympic career, but Agatha and Barbara -- who go by their first names only, following Brazilian soccer tradition -- were certainly tough competitors as the defending world champions with home court advantage.
Walsh Jennings and Ross will now face off against another Brazilian team, Larissa França and Talita Antunes, for the bronze medal on Aug. 17.
It’s one of the biggest upsets of the Rio Games so far. Here’s a look at a few more:
U.S. Women's Soccer
The U.S. Women’s soccer team was shockingly eliminated in the quarterfinals at the Rio Olympics on Aug. 12, the earliest exit for America’s national team in any major tournament.
The team suffered a loss of 4-3 to Sweden, in a penalty shootout after overtime ended with the teams tied 1-1.
Sweden’s final and winning penalty shot was kicked by Lisa Dahlvist, who was able to get past U.S. goalie Hope Solo after her teammates Alex Morgan and Christen Press missed their shots.
The elimination follows a rough couple of weeks for Solo, who was continuously boo’d by the crowd after controversial Instagram posts in which she joked about the Zika Virus. Regardless of the heckling, the 35-year-old goalie said she was “focused” on winning.
“I did know they were booing, but it doesn’t affect me,” she told Sports Illustrated. “I came here to do one thing, and that’s to help our team win, our country win. And I’m very focused in doing that.”
The loss is a huge disappointment for the team, which has won gold four times -- in 1996, 2004, 2008 and 2012 -- since women’s soccer became an Olympic sport in 1996.
Defending gold medalist Serena Williams suffered a shocking loss in the third round of the women’s singles tournament at the Rio Olympics on Aug. 9, falling to Ukraine’s Elina Svitolina, which eliminated her from the tournament.
The loss shocked the world, especially the Rio Olympics’ favorite fan, Leslie Jones, who took the elimination particularly hard.
“I'm so pissssed. Serena lost,” Jones captioned a sullen selfie. “I feel like if I was watching she would have won. Dammit!”
Williams’ loss knocks her out of medal contention and sends her home empty-handed after she and older sister Venus -- the gold medal winners in 2000, 2008 and 2012 -- also suffered a surprising loss in the doubles competition earlier in the week.
The tennis court has been the setting for big upsets on the men’s side as well, as Novak Djokovic -- who won both the French and Australian Open this year -- lost in the first round of both the men’s singles and doubles tournaments.
After the losses, the 12-time Grand Slam champion and 2008 Olympic bronze medalist announced that he would not be competing for his home country of Serbia in the mixed doubles event, leaving the 2016 Games empty-handed.
Douglas was the women’s gymnastics all-around champ in 2012, but did not have the chance to defend her title in Rio, after she failed to qualify for the finals.
The reigning gold medalist actually placed third in the all-around standings, behind teammates Simone Biles and Aly Raisman, but due to a rule that only two gymnasts from each country can compete in the finals, Douglas will have to watch from the sidelines.
"I'm not disappointed at all," she told the Associated Press on Sunday. "I have no regrets."
Douglas, who also missed the podium in the individual uneven bars competition, will leave Rio with at least one gold, however, after the American women won the team competition in commanding fashion on Aug. 9.
U.S. Men’s Gymnastics Team
The American men’s gymnastics team were not as heavily-favored as the women coming into this year’s Olympics, but they put up a good show in the team competition, recovering from shaky performances on the floor and pommel horse to start climbing the leaderboard after solid rotations on rings and vault.
Unfortunately, the comeback grinded to a halt when Danell Leyva -- who made the team just two weeks before competition began after John Orozco tore his ACL -- fell off the high bar in the middle of his routine, dashing the American men’s hope for a medal.
U.S. Field Hockey
The United States brought many dominant athletes to Rio, but no one was looking very hard at the women’s field hockey team -- that is until their victory over No. 2-ranked Argentina in the opening round.
The team -- who finished last in London in 2012 and entered the Olympics ranked No. 5 in the world -- followed that up with a win over No. 3-ranked Australia, proving they were a force to be reckoned with. Unfortunately, they ended up falling to Germany in the quarterfinal round.
Balandin of Kazakhstan shocked the world when he claimed victory in a surprising upset in the men's 200m breaststroke on Aug. 10, winning the gold, and the first-ever swimming medal for his country.
The 21-year-old swimmer, who was the slowest finalist to qualify for the event, beat out American Josh Prenot for the gold medal by just 0.07 seconds. Russian swimmer Anton Chupkov took home the bronze in a close third. Only 0.24 seconds separated first place from third.
Joseph Schooling met Michael Phelps as a 13-year-old swimming fan in 2008. Eight years later, he beat his childhood idol in the 100m butterfly, touching just ahead of Phelps, Chad le Clos and Laszlo Cseh, who would tie for silver.
“What a race!! Congrats to @josephschooling !!!” Phelps wrote on Instagram after the event. We've got an updated pic!! Best of luck bro!! I'll be watching!”
Jamaica is home to the greatest sprinters in the world. That’s just fact. For the last two Olympics, that has meant two names in particular: Usain Bolt in the men’s races, and Shelly-Ann Fraser-Pryce for the women. While Fraser-Pryce lost her title on Aug. 13, it won’t go far.
Her fellow countrywoman, 24-year-old Elaine Thompson, won the gold in the 100m sprint in Rio, finishing .15 second ahead of Fraser-Pryce, who took third. American runner Tori Bowie took the silver.