Summer Olympics 2016: Gold-Medal-Winning Americans Most Likely to Repeat in Rio

How hard is it to repeat as an Olympic champion?

It's hard enough just to make it back to the Games, much less the top of the podium.

Each year, the NFL has the Super Bowl and baseball the World Series. Unlike other sports with annual championships, Olympic athletes have four years to age, get deeper in debt, lose motivation, be exposed as participants in a state-supported doping system (see: Russia).

The U.S. delegation of 555 athletes in Rio, the biggest of any nation, includes 53 American athletes who will attempt to defend their Olympic titles.

The American team will rely heavily on repeat contenders to return to the top of the podium. The U.S. is aiming, like it always does, to top the medal count again like it did in 2012. In London, the U.S. easily bested the field in overall medals (104) and golds (46). China followed with 88 overall (38 gold), and Russia collected 82 overall (24 gold).

And while the U.S. team will have plenty of athletes familiar with the color gold, there are athletes from other countries hoping to score another gold medal as well. To make our selections, we considered various factors like strength of competition, previous Olympic or international experience, comparative scores and times, injury status and age.

With that criteria in mind, here are the Olympic champions most likely to repeat in Rio.

Serena Williams, Tennis

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Serena Williams will try to become the first repeat singles gold medalist in Olympic history.

Since the sport returned to the Games in 1988, Williams has won four of the U.S. team's 13 Olympic gold medals. Three came with her older sister, Venus, in doubles (2000, 2008, 2012).

Serena won her lone singles gold in 2012, completing the "Career Golden Slam" of four majors and the Olympics.

Recent Wimbledon victories in singles and doubles may represent a turnaround in a season that has been less dominant than usual for Williams, who still maintains the world's No. 1 ranking.

Given her spotty results this season, the Olympic tournament field could present some challenges to a repeat bid in both singles and doubles.

In singles, Williams is 1-2 in major finals this year, beating Germany's Angelique Kerber to win Wimbledon (on grass) in June but losing to Kerber earlier this year in January's Australian Open (hard courts) and to Spain's Garbine Muguruza in the French (clay) in spring.

The Olympic tournament will be held on hard courts, the surface where Williams has also suffered losses in 2016 to Victoria Azarenka at Indian Wells and Svetlana Kuznetsova in Miami.

In doubles, Slovenians Katarina Srebotnic and Andreja Klepac defeated the Williams early on the clay in Rome, but the sisters beat them in Wimbledon's first round en route to the title.

Even though some argue tennis does not belong in the Games—many players covet the majors (the Australian Open, French Open, Wimbledon and U.S. Open) more—the Olympics hold a special place of honor for Williams, 34.

She has said if her house caught fire, the first thing she'd save are her medals.

Michael Phelps, Swimming

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Michael Phelps comes into his record-tying fifth Olympic Games saying he's happier and more motivated than ever before. But is he still fast enough, at age 31, to win?

The newly minted first-time Olympic swim team captain (with five others) and the owner of all-time marks in total medals (22) and golds (18) showed he still has it—in at least some events—at the U.S. trials, when he qualified for three individual events. Phelps is expected to swim in the 4X100-meter medley relay. Reports from USA Today and Olympic Talk also have him joining the 4X100m freestyle and possibly 4X200m freestyle relays.

Phelps should be able to help the U.S. defend gold swimming the butterfly leg in the 4x100-meter medley relay, an event the U.S. men have never lost (not counting the boycotted 1980 Games). At the most, there's a chance for individual golds in the 100- and 200-meter butterfly and 200-meter individual medley, all events he won at the trials.

Phelps is in the ballpark, swimming the world's second-fastest times of the year in the 100m fly (51.00 seconds to Hungarian Laszlo Cseh's 50.86) and 200m IM (1:55.91 to Japanese Kasuke Hagino's 1:55.07) at trials, narrowly out-touching rival Ryan Lochte (1:56.22).

He posted the year's sixth-fastest time in the 200m fly, almost two seconds behind Cseh's 1:52.91.

But he says he can do better.

Phelps has come a long way—down, then up—after saying he was done swimming following the 2012 London Games, where he won four golds and two silvers. His life hit bottom as he was arrested for DUI in 2014 (his second in 10 years) and told ESPN The Magazine that he had suicidal thoughts. Phelps checked himself into a rehab facility, later saying the results changed his life.

He is now a new dad to a son named Boomer with fiancee Nicole Johnson and insists this Olympics will be his last.

U.S. Women's Basketball Team

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There hasn't been a U.S. Olympic team, in any sport, more dominant than this one.

The U.S. women's basketball squad has won five straight gold medals and own a win streak of 41 consecutive Olympic games (with a lowercase "g").

With aging stars in Sue Bird, Tamika Catchings and Diana Taurasi, the team is bringing in young blood like Elena Delle Donne, the 2013 WNBA Rookie of the Year, and yet another UConn star in four-time NCAA champion and 2016 WNBA draft No. 1 pick Breanna Stewart.

The team is so deep that two-time gold medalist Candace Parker, 30, was left off the squad despite leading the 2012 gold medalists in rebounds and blocked shots and finishing as the USA's third-leading scorer.

The U.S. went 4-0 on its pre-Olympic exhibition tour, delivering blowouts to rival Australia, 104-89; France, 84-62 and Canada, 83-43 last week. A team of young WNBA stars managed to keep it close, 88-84. In London, the U.S. beat France for 2012 gold while Australia won bronze.

Liz Cambage, 24, formerly of the WNBA Tulsa Shock and recently playing for Shanghai of the Women's Chinese Basketball Association, and Penny Taylor, 35, lead the Australians with the retirement of stalwart Lauren Jackson. But Taylor just announced her own retirement, saying this would be her last WNBA season. She was a big part of the Opals' 2006 world championship team and helped the Phoenix Mercury to three WNBA titles.

France, the world's No. 4-ranked team behind the U.S., Australia and Spain, struggled in the pre-Olympic tuneup, losing to both Australia and No. 9 Canada.

Katie Ledecky, Swimming

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Four years ago, no one saw this coming.

Not even royal couple William and Kate, the Duke and Duchess of Cambridge, who arrived to watch what they assumed would be Britain's Rebecca Adlington win gold in the 800-meter freestyle in London.

At the beginning of the London Games, Ledecky was just a new name on a loaded U.S. swim team, a 15-year-old overshadowed by another teen, personable phenom Missy Franklin. But Ledecky blew away Adlington in a shocking upset en route to gold. That was just the start.

Ledecky has dominated women's distance swimming like no one else in history. She startled longtime observers of the sport by winning 2015 world titles in four events (200, 400, 800, 1,500), becoming the first person to sweep those events. Her margins of victory—sometimes a half-pool length against top swimmers—are remarkable.

She holds world records in the 400, 800 and 1,500 (not contested at the Olympics). It's no stretch to say she's the favorite to come home with gold in four events—three individual freestyles and the 4x200-meter freestyle relay.

Consider her winning margins of last year's world championships, against the world's best swimmers. She won the 1500 in a time of 15 minutes, 25.48 seconds over New Zealand's Lauren Boyle, who posted a time of 15:40.14. That's almost a 15-second gap. In the 800, Boyle was more than 10 seconds back.

Nearly four seconds separated Ledecky from her closest competitor in the 400, the Netherland's Sharon Van Rouwendaal. For context, the next three competitors were separated by 1.04 seconds.

Ledecky is so dominant at the distance events, she is seeking new challenges in the shorter ones, swimming the 200 at worlds and beating accomplished sprinters and middle-distance racers. Her time of 1:55.16 edged Italy's Federica Pellegrini, the 2008 gold medalist, and U.S. teammate Missy Franklin, the star of the 2012 Games (four gold, one bronze) and 2012 trials runner-up in the event.

U.S. Women's Water Polo

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After winning everything but Olympic gold since the sport debuted in 2000, the U.S. team finally made it to the podium's top step in London. Since then, it hasn't looked back.

The U.S. is the first women's water polo team to sweep all four majors—World League, World Cup, world championship and Olympics—and is an overwhelming favorite to defend gold in Rio.

No nation has successfully defended its women's water polo title at the Olympics. The Americans' closest rivals are Spain, ranked No. 2 in the World League standings, followed by Australia and China.

But the Australians are responsible for the U.S. team's only two losses this year. The Americans beat Spain, 13-9, to take the World League title in June.

The team is backstopped by long-armed goalie Ashleigh Johnson, a gifted all-around athlete and Jamaican-American who grew up near Miami. She is the first person of color on the U.S. women's water polo team.

Johnson, 21, took the year off from studies at Princeton last year to train on a team typically loaded with Californians.

Also look for her teammate, 17-year-old Aria Fischer, who is the youngest American woman to play on a Summer Olympics team (hockey player Lyndsay Wall was 16 at the 2002 Winter Games).

U.S. Men's Basketball

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With some of the game's biggest names missing from Rio (LeBron James, Steph Curry, Kawhi Leonard, James Harden, Russell Westbrook, Chris Paul among them), you might think this sounds familiar—as in the 2004 Games.

That's when the U.S. team wound up with Olympic bronze, losing to Puerto Rico in the opener and barely beating host Greece despite fielding a squad of young NBA stars like Dwayne Wade, Carmelo Anthony and a teenage James.

But this isn't then.

With a proven system in place and leadership from Jerry Colangelo and coach Mike Krzyzewski (his last Games—Gregg Popovich will coach in 2020), this team of A- and almost-A-listers should repeat as Olympic champions and extend the United States' gold medal streak to three.

Rio's squad includes Kevin Durant, Draymond Green, Kyrie Irving, Paul George, Klay Thompson, Anthony, DeMarcus Cousins, Jimmy Butler.

So Spain, Serbia, world No. 3-ranked Lithuania, Argentina and France shouldn't be licking their chops. Not too much.

World No. 2 Spain will be the biggest challenge, with a ton of international experience and players like Pau Gasol (brother Marc is injured), Ricky Rubio, Jose Calderon, Sergio Rodriguez and Juan Carlos Navarro.

Tony Parker and Boris Diaw will lead fifth-ranked France. Manu Ginobili, the star of the 2004 Olympic champions—and chosen to carry the Opening Ceremony flag in 2008—is back with Luis Scola to lead fourth-ranked Argentina. The U.S. defeated Argentina, 111-74, in an Olympic tuneup, and won contests with China and Venezuela by huge margins.

U.S. Women's Gymnastics Team

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Winning consecutive team gold, as this team is heavily favored to do, will not only cement the U.S. women as a dynasty but make history. No U.S. gymnastics team has won two straight Olympic titles.

China, Russia and Great Britain are listed as contenders for the title—China and Great Britain finished 2-3 behind the U.S. at the 2015 world championships—but don't believe it. They, along with Russia, are battling for the podium's lower steps.

Perennial Olympic medalists Romania (the team of "Perfect 10" Nadia Comaneci and winner of five world titles in seven years), surprisingly did not qualify a full squad.

The U.S. team, runaway winners of the last two world championships, features three-time world all-around gold medalist Simone Biles.

It's also the squad's depth that's impressive. Only injury or a shocking collapse will keep this team from matching 2012's "Fierce Five" gold. Two members of that team, 2012 all-around Olympic champion Gabby Douglas and floor gold medalist Aly Raisman, return.

Biles, bars expert Madison Kocian and fan favorite Laurie Hernandez, who may steal the spotlight from Biles, are Olympic first-timers.

Jordan Burroughs, Wrestling

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With three world titles and one Olympic gold, Jordan Burroughs, 28, is on a mission to become the most decorated U.S. wrestler in history.

He's chasing two-time Olympic champion John Smith, who also won four world championships. Burroughs (74 kg; 163 lbs) is 24-1 in world and Olympic competition since 2011 and has already committed to the 2020 Games in Tokyo.

He was so dominant that his two biggest U.S. rivals moved up to the 86-kilogram weight class at this year's Olympic trials to try to earn an Olympic berth.

Burroughs' biggest rival is Russian Denis Tsargus, the only wrestler to blemish his record when he beat Burroughs, who was wrestling with an injured knee, in the semifinals of the 2014 world championships. But the showdown won't happen in Rio. Another Russian, world bronze medalist Aniuar Geduev, beat Tsargus in the Russian Championships, earning the Olympic berth. (Countries are allowed to send only one wrestler per weight class.)

Geduev narrowly lost to Burroughs, 4-3, in last year's world championships.

This is Burroughs' first Olympics since becoming a father. He has two children.