Threat Meter: Who poses the biggest challenge to Team USA at Rio Olympics?

SI's staff ranks the biggest threats to Team USA's predicted gold-medal wins on a scale of one to five.

SI’s Brian Cazeneuve predicted that the U.S. would bring home a total of 118 medals from the Rio Olympics, with 45 gold. Which country or athletes pose the biggest challenge to that number? Our writers rank each threat from one to five, with one being the lowest threat and five being the highest.

Threat level: 5

Women’s track and field, 400 meters

Favorite: Allyson Felix
Biggest challengers: Shaunae Miller (Bahamas), Caster Semenya (South Africa)

Felix is the defending world champion, but her training was compromised by an ankle injury. Miller has the fastest time in the world this year (49.55) and Semenya, if she runs, could be dominant. — Tim Layden

Shooting, double trap

Favorite: Joshua Richmond
Biggest Challenger: Vasily Mosin (Russia)

Half a dozen shooters have a shot at winning here. James Willett of Australia and Alessandro Chianese of Italy are two more. — Brian Cazeneuve​

Threat level: 4

Men’s swimming, 200-meter breaststroke

Favorite: Josh Prenot
​Biggest challenger: Marco Koch (Germany)

Prenot’s strong finish should hold off Koch. He’ll also get a good push from U.S. teammate Kevin Cordes, who will likely be ahead at 100 meters. — B.C.

Women’s swimming, 200-meter freestyle

Favorite: Katie Ledecky
Biggest challenger: Sarah Sjostrom (Sweden)

The shorter the race, the more vulnerable Ledecky is. Sjostrom is peaking and Italian veteran Federica Pellegrini could always contend. — B.C.

Women’s swimming, 100-meter breaststroke

Favorite: Lilly King
Biggest Challenger: Ruta Meilutyte (Lithuania)

With banned Russian Yulia Efimova out of the picture, King’s path is easier, but it’s a new pressure level for the Olympic rookie. — B.C.

The slow descent of Houston McTear, the greatest natural sprinter ever

Men’s track and field, 400 meters

Favorite: LaShawn Merritt (USA)
Biggest challengers: Kirani James (Grenada) and Wayne Van Niekerk (South Africa)

James won the Olympic gold medal in 2012 and Van Niekerk the world title in 2015. Merritt is at the top of his game, but this is a hyper-competitive event.— T.L.

Men’s track and field, 400-meter hurdles

Favorite: Kerron Clement (USA)
Biggest challengers: Michael Tinsley (USA), Javier Culson (Puerto Rico)

Clement is a terrific big-race performer with two world titles and 2008 Olympic gold, but this is a wide-open, contentious race. — T.L.

Women’s track and field, 4x100 relay

Favorite: USA
Biggest challenger: Jamaica

Team USA broke the world record in winning the 2012 gold, and will be very strong again. But Jamaica, with budding star Elaine Thompson, will push the USA to the line. It comes down to baton passes. — T.L.

Women’s freestyle wrestling (75kgs)

Favorite: Adeline Gray
Biggest Challenger: Zhou Qian (China)

Two-time world champ Gray will have to go through Zhou and home favorite Aline da Silva in order to earn her prize. — B.C.

Olympic wrestler Adeline Gray talks training regimen, Rio and more

​

Men's Golf

Favorite: Bubba Watson
Biggest Challenger: Sergio Garcia (Spain)

Bubba can overpower the Olympic course like no other but is such a finicky character Rio may not agree him. Garcia, famously major-less, can brighten his legacy with gold and he has always brought his A-game playing for his flag.— Alan Shipnuck​

Rowing, women’s eight

Favorite: United States
Biggest challenger: Great Britain

The Brits made a charge on the Americans at the World Cup in May, but the U.S. depth should be enough to bring a third-straight gold medal. — Rich O'Brien

The Unbeatables: U.S. women’s eight is the most dominant team in Rio

​

Shooting, men’s 50-meter rifle, three positions

Favorite: Matt Emmons
Biggest challenger: Zhu Qinan

High energy Emmons will have his hands full with both Zhu and Hui Zicheng of China. He’s a good pressure competitor. — B.C.

Shooting, men's skeet

Favorite: Vincent Hancock
Biggest challenger: Gabriel Rossetti (Italy)

Two-time champ Hancock is the first shooter to win consecutive golds in skeet, but the Italian team is very strong. — B.C.

Nathaniel S. Butler/NBAE via Getty Images

Threat level: 3

Men's Basketball

Favorite: USA
Biggest Challenger(s): Spain, Croatia

Spain has a roster full of international veterans, Croatia has a young team that should be sneaky exciting, and an upset is at least possible. Still, let's be clear: the U.S. men are a thousand miles more talented than anyone else here. — Andrew Sharp

Who will save Olympic basketball? Seven NBA players to watch in Rio

​

Men’s swimming, 100-meter butterfly

Favorite: Michael Phelps
Biggest Challenger: Laszlo Cseh (Hungary)

Cseh has been trying to catch Phelps in the fly and IM for eight years. His times are faster this year, but Phelps knows how to win big races. — B.C.

Women’s swimming, 4x200-meter freestyle relay

Favorite: U.S.
Biggest Challenger: China

The U.S. has some muscle here with the likes of Ledecky and Missy Franklin, but the Chinese strength will be a mystery until they arrive. — B.C.

Rainbows, Unicorns and a Shark: Link between Katie Ledecky, Missy Franklin

​

Women’s track and field, 100-meter hurdles

Favorite: Brianna Rollins
Biggest challengers: Kristi Castlin (USA), Nia Ali (USA)

This event looms as a sweep for the USA, but Rollins is fastest of the three. Fastest of all is world record-holder Keni Harrison (USA), who did not make the U.S. team. — T.L.

Women’s track and field, 400 hurdles

Favorite: Dalilah Muhammad
Biggest challenger: Janieve Russell (Jamaica).

Muhammad has the fastest time in the world by more than a full second, but any race in which 10 barriers are placed in a runner's path is at least a little uncertain. — T.L.

After the Lightning: Track and field’s newest stars ready for the spotlight

​​

Women’s track and field, high jump

Favorite: Chaunte Lowe
Biggest challenger: Kamila Lucwinko (Poland), Marie-Laurence Jungfleisch (Germany)

Lowe, a mother of three children, won the U.S. trials in July and has the best jump in the world in 2016. But the high jump is notoriously funky and subject to surprise winners. — T.L.

Boxing, women’s 75 kg

Favorite: Claressa Shields
Biggest Challenger: Savannah Marshall (Great Britain)

Marshall handed Shields her only loss, on the way to becoming Britain’s first female world champ. But that was in 2012. Shields is a stronger, more complete fighter now. — R.O.

​

Threat level: 2

Women's Tennis (Singles)

Favorite: Serena Williams
Biggest Challenger: Garbine Muguruza (Spain)

Serena might turn 35 in September but she is the world No. 1, the defending gold medal winner and the champ at Wimbledon last month, i.e., the most recent Major. Invincible, she's not (especially on days her accuracy is off) but it would take a Herculean effort to beat her. Especially on a hard court. — Jon Wertheim

Men’s swimming, 4x200-meter freestyle relay

Favorite: U.S.
Biggest Challenger: Australia

The U.S. quartet has medaled in all 23 non-boycotted Olympics and the team’s depth is second-to-none. — B.C.

Women’s swimming, 400-meter freestyle

Favorite: Katie Ledecky
Biggest Challenger: Leah Smith (U.S.)

Ledecky beat Smith by nearly two seconds at Trials in Omaha and she was comfortably coasting at the end. Can she pull Smith to silver? — B.C.

The Longest Run: Olympics about more than winning for Refugee team

Women’s triathlon

Favorite: Gwen Jorgensen
Biggest Challenger: Helen Jenkins (Great Britain)

Jorgensen has been on the podium in 17 straight international races, winning 15 of them. — B.C.

Women’s water polo

Favorite: U.S.
Biggest Challenger: Australia

After some early narrow misses at gold, the defending world and Olympic championships have been the dominant squad over the last quad. — B.C.

Men’s freestyle wrestling (74kgs)

Favorite: Jordan Burroughs
Biggest Challenger: Aniuar Geduev (Russia)

Burroughs is 24–1 in matches at Worlds and Olympics since 2011. He will likely go down as one of the best ever. — B.C.

Men’s track and field, triple jump

Favorite: Christian Taylor
Biggest challengers: Will Claye (USA)

Taylor lost to Claye, his former Florida teammate, at the US Trials, but has been the best triple jumper in the world for half a decade. — T.L.

Men’s track and field shot put

Favorite: Joe Kovacs
Biggest challengers: Ryan Crouser (USA), Stephen Mozia (Nigeria)

Kovacs, the 2015 world champion, has been the most consistent thrower in the world for the last two seasons. He is a deserving favorite. — T.L.

Women’s track and field, long jump

Favorite: Brittney Reese (USA)
Biggest challengers: Sosthene Moguenara (Germany)

Reese is the defending gold medalist and a three-time world champion. She has been at the best long jumper in the world for eight years and, at age 29, is at the peak of her game. — T.L.

Rio’s Olympians: Like the city, its athletes overcoming own obstacles

Threat level: 1

Women's Tennis (Doubles)

Favorite: Serena and Venus Williams
Biggest Challenger: Sara Errani and Roberta Vinci (Italy)

Williams-Williams no longer play together regularly. But when they do, it's usually a joy to behold. Wearing smiles and giggling like sisters in the backseat, they crush the balls and, by extent, their opponents. The occasion also serves to highlight their absurd and soaringly triumphant backstory (the two best players of the last 20 years are really siblings?) Coming off gold in London and the tittle at Wimbledon last month where they synchronized their gears, Williams-Williams is again the team to beat. — J.W.

Women's Basketball

Favorite: USA
Challenger(s): Australia, Spain

Australia's 6'8 Liz Cambage is one of the only international players who could hang with the U.S. women up front, and the Spanish team won the silver at the world championships in 2014. But do you realize how dominant the U.S. women have been? They haven't lost an Olympic game since 1992, and with veterans like Sue Bird and Diana Taurasi pairing with Elena Delle Donne and Brittany Griner, this might be the most dominant roster yet. — A.S.

Men’s swimming, 4x100-meter medley relay

Favorite: U.S.
Biggest Challenger: Australia

This U.S. team has never been beaten in 13 Olympics. No other team has swimmers from very good to great in all four strokes. — B.C.

Women’s swimming: 800-meter freestyle

Favorite: Katie Ledecky
Biggest Challenger: Jessica Ashwood (Australia)

Ledecky’s stamina is crushing in the longer races. She could step out halfway to watch tennis and still win. — B.C.

Back to her roots: How Katie Ledecky became so dominant in the pool

​

Men’s track and field, 4x400-meter relay

Favorite: USA
Biggest challengers: Jamaica, Trinidad and Tobago, Bahamas

In 2012, the Bahamas stunned the USA, which has won this race in 12 of the last 16 Olympics, and always has the deepest roster of quarter-milers. — T.L.

Men’s track and field decathlon

Favorite: Ashton Eaton
Biggest challengers: Unexpected injury or no-height in pole vault

Eaton, the world record holder and defending gold medalist, has become the greatest decathlete in history. His is the surest gold medal in the track competition at the Games. — T.L.

Women’s track and field, 4x400 relay

Favorite: USA
Biggest challenger: Jamaica

The USA hasn't lost the gold in this event since 1992. That streak should not end here. — T.L.