The 27-year-old middle distance runner from Kenya won a gold medal in the 800m at the London 2012 Olympics, and he’s a favorite for the race at this year’s games. He proved he was still on form when he won the 800m at last year’s World Championships in Beijing, and holds a world record having run the distance in just under one minute and 41 seconds.

The South African runner looks set to smash a long standing world record for the women's 800m. But Semenya’s speed has put her under scrutiny. She was forced to undertake gender testing in 2009 and had to take hormones to balance out her naturally high testosterone levels. But a fellow athlete’s court case last year ruled that it was discriminatory to penalise athletes for genetic advantages.

Niger has only won an Olympic medal once for boxing at the Munich Games back in 1972. This year the West African country has sent six athletes to Rio - two swimmers, two runners and two martial artists. Judoku Ahmed Goumar and Taekwondo athlete Abdoulrazak Issoufou Alfaga (pictured)

South African swimmer Chad le Clos became a surprise star at the London 2012 olympics when he edged out his hero, reigning champion Michael Phelps, to win the gold medal in the 200m butterfly. Le Clos’ victory was almost overshadowed by his father’s joyful reaction, which made him a media sensation. In the run up to this year’s Games, le Clos confirmed that both his parents were battling cancer.

The Kenyan long distance runner won this year’s London marathon as well as last year’s Berlin marathon and the Hamburg marathon in 2013, which was his debut. He switched to road running after failing to make Kenya’s 2012 Olympic team, and is now the favorite to win the long distance race in Rio this year.

Ten athletes make up the first ever refugee team. Two Syrian swimmers, two judokas from the Democratic Republic of the Congo, a marathoner from Ethiopia and five middle-distance runners from South Sudan will compete under the Olympic flag. International Olympic Committe President Thomas Bach said the team would be "a symbol of hope for all the refugees in our world" during the current crisis.

Six of the smallest delegations at this year’s Games come from African countries. Chad, Equatorial Guinea, Liberia, Mauritania, Somalia and Swaziland are all sending just two athletes each to Rio. All are sprinters apart from Equatorial Guinean Reina-Flor Okori, who will compete in the 100m hurdles. She also holds French citizenship and has competed for France in the discipline.

Senegal is the only African country to qualify for Olympic women’s basketball this year. The team proved its credentials by winning the AfroBasket Women competition in Yaounde, Cameroon last year. The athletes will compete against twelve other teams in Rio. The last time Senegal’s female basketball players reached the Olympics was in 2000, when the team took 12th place.

The South African sprinter is a clear contender for a gold medal in Rio. He holds the world record for the men’s 400m race, and was the first athlete ever to run 100m in less than ten seconds, 200, in less than 20 seconds, and 400m in less than 44 seconds. Even champion sprinter Usain Bolt has praised van Niekerk’s racing times.