Jessica Ennis
Britain's Jessica Ennis will begin the defence of her heptathlon title on Friday but will face a stiff challenge from Brianne Theisen-Eaton, world leader this year. The Canadian’s husband, US star Ashton Eaton, will be bidding to complete a family affair with victory in the decathlon, which starts on August 18.
Shelly-Ann Fraser-Pryce
Saturday will see another star chasing three-peat immortality when Jamaica’s Shelly-Ann Fraser-Pryce attempts to complete an unprecedented hat-trick of Olympic gold in the woman’s 100m. The 29-year-old could face a stiff challenge from compatriot Elaine Thompson, the fastest woman in the world this year with a time of 10.70 seconds.
Dafne Schippers
Flying Dutchwoman Dafne Schippers could also be in the hunt for medals, but is widely seen as the bigger threat in the 200m.
Tirunesh Dibaba
The first of 47 Gold medals — and 141 overall — will be decided on Friday with the women's 10,000m, where Ethiopia’s defending champion Tirunesh Dibaba will attempt to make Olympic history by becoming the first woman to win three consecutive times in an individual athletics event. Dibaba’s tilt at history is just one of several compelling storylines unfolding over the second week of the Games.
Mo Farah
Britain's Mo Farah will attempt to retain his 10,000m crown four years after his memorable romp to glory in london.