AIPS list of 10 candidates for best athlete in the world based on their 2015 performances.

Simone Biles, USA, Gymnastics, 18

In 2015, Biles became the first woman to win the world all-around gymnastics title three times by blowing away the competition at the worlds in Glasgow, Scotland in November. Biles also won golds in the team, balance beam and floor exercise competitions. She took a bronze in the vault as well. It also marked the third straight year in which Biles won the floor exercise event. The 18-year-old Columbus, Ohio native now has 14 worlds, including ten golds to her credit. Though she was too young to compete at the London Olympics, she has established herself as a clear favorite in Rio.

Novak Djokovic, Serbia, Tennis, 28

Widely considered one of the greatest tennis players ever and perhaps the best returner in history, Djokovic won three majors, six masters and 11 titles in 2015. He won the Australian Open, Wimbledon and the U.S. Open and was a finalist at the French Open. He beat Federer in straight sets winning his fifth World Tour Finals title and became the first player to win four consecutive end-of-year finals tournaments. 

Usain Bolt, Jamaica, Athletics, 29

Even without breaking either of his world records in the 100 and 200-meter runs, the greatest sprinter in history seemed to have gotten better in 2015. Bolt went undefeated for the second straight year, winning three gold medals at the world championships just at the time when people are expecting him to slow down. Bolt was undaunted when a cameraman inadvertently took him to the ground while he was taking a victory lap after winning the 200 meters. Just two days later, he anchored the Jamaican relay team to another gold medal in the 4x100-meter relay.

Ashton Eaton, USA, Athletics, 27

Eaton won the 2015 world title in the decathlon improving his own world record with a 9045-point performance in Beijing. He is an American decathlete and Olympic champion, who holds the world record in both the decathlon and indoor heptathlon events, and is only the second decathlete (after Roman Šebrle) to break the 9,000-point barrier, with 9,039 points. On August 29, 2015, he beat his own world record with a score of 9,045 points.

Neymar da Silva Santos Junior, Brazil, Soccer, 23

Due to having the mumps, Neymar was expected to miss the 2015 UEFA Super Cup and the 2015 Supercopa de España. On 17 October 2015, Neymar scored four goals in Barcelona's 5–2 home win over Rayo Vallecano in La Liga, taking his total to eight goals for the season. On 21 November, Neymar scored one and provided a back heel assist for Iniesta in Barcelona's 4–0 away win against Real 

Lydia Ko, New Zealand, golf, 18

On Feb. 2, the Korean-born New Zealander became the youngest player of either gender to be ranked No. 1 in the history of ladies golf (at 17 years, 9months and 8 days), and on Sept. 13, she became the youngest to win a major title, The Evian Championship, at age 18 years, 4 months and 20 days. Her closing round of 63 was the lowest final-round score for the winner of an LPGA major championship in history. In November she won the LPGA Rolex Player of the Year award, making her the youngest golfer ever to win that award.

Katie Ledecky, U.S., swimming, 18

The teenager from Washington, D.C. confirmed her place as the world’s best swimmer by winning five gold medals and breaking three world records at the world championships in Kazan, Russia this summer. Ledecky is now arguably the most versatile freestyle swimmer, male or female, ever to enter a pool. She won individual events at 200, 400, 800 and 1,500 meters and anchored the U.S. team to gold in the 4x200-meter freestyle relay. Ledecky has now lowered the world mark in the 1,500 three times, dropping the mark to 8 minutes, 7:39 seconds. In so doing, she finished an astounding 14.66 seconds ahead of the field.

Carli Lloyd, U.S., soccer, 33

Lloyd became the first woman to score three goals in a world cup final, leading the U.S. women to victory against Japan, 5-2, in the decisive match. Lloyd has now scored the game-winning tallies at the most recent world cup and the last two Olympic Games. She won the Golden Ball Trophy as the top player during the tournament.

Serena Williams, U.S. tennis, 34

She was the Sportswoman of the Year, according to Sports Illustrated and at 34, she is making a case to be considered the greatest female tennis player in history. Williams won titles at the Australian Open, French Open and Wimbledon, increasing her total of Grand Slam singles titles to 21, third-best behind Margaret Court’s 24 and Steffi Graf’s 22. Though she was upset later in the year at the U.S. Open, Williams maintained the World No. 1 ranking for the entire season, repeating her feat of 2014.

Saori Yoshida, Japan, wrestling, 33

Yoshida won her 11th straight world title in 2015. She has also won gold at all three Olympic Games in which women’s wrestling has been contested. She has lost only two matches in her career – to Marcie Van Dusen of the U.S. in 2008 and Valeria Koblova of Russia in 2012. Yoshida was Japan’s flag bearer at the 2012 Olympics in London.