Biles seeks to extend Olympic gold rush as Duplantis targets world record
Biles, widely considered the greatest gymnast in history, can end all debate if she triumphs in the balance beam and floor exercises at the Bercy Arena.
The 27-year-old on Saturday claimed her third gold in Paris, winning the vault to take her overall Olympics tally to seven golds.
Her astounding achievements come just three years after she famously imploded in Tokyo, suffering from the debilitating mental block known as the "twisties."
Hailed by many for prioritising her mental health, some also criticised Biles as a quitter three years ago.
As she burnishes an Olympic legacy launched with four golds in Rio, Biles has noticed the critics are silent.
"They're really quiet now, so that's strange," she said with a laugh after winning vault gold.
The veteran admits she is "getting old" but is tempted to compete in her home Olympic Games in Los Angeles in four years' time.
Pole vault king
Sweden's Duplantis is similarly dominant in pole vaulting and is likely to be competing against himself as much as the rest of the field as he pushes for a ninth world record.
The 24-year-old US-born prodigy has been practically unbeatable in the event for five years after finishing with a silver medal at the 2019 World Championships in Doha.
The main question over Duplantis is just how high he can go. He set a new world record of 6.24 metres earlier this season.
The reigning Olympic champion said he is comfortable with being the overwhelming favourite to win at the Stade de France.
"You just get used to it. Every competition I go to I'm going to be a big favourite. It is what it is. The reason for that is that I have been showing it as well.
"I go into every competition trying to jump as high as I possibly can. I think it should be enough to do what I know I can do. You get used to it and you know how to control it."
Dutch runner Sifan Hassan goes in the final of the women's 5,000m, as she hunts a golden treble of 5,000, 10,000m and marathon to match Czech athlete Emil Zatopek, who achieved the feat at the 1952 Helsinki Games.
The defending champion qualified second-quickest in 14min 57.65sec, behind Kenya's Faith Kipyegon, the two-time defending 1,500m champion.
She also went for a treble in Tokyo, winning the 5,000m and 10,000m but only managed bronze in the 1,500m.
Track cycling begins at the National Velodrome with the first gold on offer in the women's team sprint.
Britain have topped the cycling medals table at every Games since Beijing in 2008 but are without retired greats Laura and Jason Kenny, who won 12 gold medals between them, and Katie Archibald, who broke her leg in a freak accident.
The badminton competition at the Paris Games comes to an end with the finals of the men's and women's singles.
China's He Bingjiao takes on South Korean top seed An Se-young for women's gold before defending men's champion Viktor Alexsen of Denmark faces Thailand's Kunlavut Vitidsarn.
The men's football tournament is at the semi-final stage, with Morocco taking on Spain in Marseille before Thierry Henry's France face Egypt in Lyon.
In a boost for organisers, the mixed relay in the triathlon will go ahead on Monday after pollution levels in the River Seine were deemed sufficiently low for the swimming leg.