US gymnastics star Simone Biles launches her bid for Olympic immortality at the Tokyo Games on Sunday as surfing and skateboarding make their debuts as part of a drive to attract young audiences.
American swimmer Chase Kalisz won the first of 18 gold medals up for grabs on day two of the Games as Japanese tennis star Naomi Osaka prepared to return to the court after her self-imposed exile.
The Ariake Gymnastics Centre will be the setting as Biles, 24, starts her bid to become the first woman in more than half a century to retain the all-around title.
The American could leave Tokyo with a career haul of nine Olympic gold medals, equalling the record set by Soviet gymnast Larisa Latynina in Tokyo in 1964.
Biles has not lost an all-around competition since 2013, an eight-year spell that has encompassed 19 world championship titles and four Olympic golds.
In acknowledgement of her domination, Biles has been awarded her own emoji on Twitter — a goat in a leotard symbolising her status as the GOAT, or greatest of all time.