It was the sixth time McLaughlin-Levrone had broken the world record, lowering her previous mark of 50.65 set at the U.S. trials in June.
Lyles, who had been bidding to complete a 100m-200m double in Paris, was taken off the track in a wheelchair following the race, won by Botswana's Letsile Tebogo.
The 26-year-old, who had claimed virtually every other title in an utterly dominant half decade including three world championship gold medals, clocked 12.99 seconds.
A tense game ended all square at 1-1, with fourth-quarter goals in quick succession from Dutch captain Thierry Brinkman and Germany's Thies Prinz.
Nadeem threw an Olympic record of 92.97 metres for victory, India's defending champion Neeraj Chopra taking silver with 89.45. Grenada's Anderson Peters claimed bronze with 88.54m.
Marathon swimming is set to get underway amid concerns over water pollution in the river Seine.
There will be 21 medals up for grabs with the bulk of them being given out in athletics.
"The last hurrah, I'm done. I've always said I want to retire a champion, that's it," Harrington told Irish national broadcaster RTE.
Alfred is seeking to emulate Jamaica's Elaine Thompson-Herah, who did the 100m-200m double at the Rio 2016 Games and at the Covid-delayed Tokyo Olympics.
Hosts France knocked out Argentina on Friday to avenge the country's defeat in the last World Cup final in a bitter rivalry recently fuelled by a video of Argentine players directing chants labelled as racist at French players.
Coached by Carl Lewis and the first European to win the NCAA title in the United States, Hinchliffe finished strongly and Lyles, not exactly easing up, took second in 10.04 to also go through safely.
Wasick first represented Poland at the 2008 Beijing Games and has since competed in London, Rio and Tokyo before arriving in Paris with one of the fastest times in the 50 freestyle.
"We are talking about women's boxing. We have two boxers who were born as women, raised as women, who have passports as women and who have competed for many years as women and this is a clear definition of a woman," Thomas Bach told a press conference.
Simone Biles is set to compete for her third gold medal, this time on the vault, while China's Zheng Qinwen is aiming to make history by taking the country's first gold medal in women's tennis singles.
They started dating in 2020 but recently were rumoured to have split. "That's our personal life so you don't need to know that," said 29-year-old Siniakova.
The Frenchman becomes the first male swimmer since American record-breaker Michael Phelps at Beijing 2008 to win four individual golds in a single Games.
The 17-year-old hit the wall in an Olympic record 2min 03.03sec ahead of America's Regan Smith (2:03.84) and Chinese defending champion Zhang Yufei (2:05.09
Andy Murray's trophy-filled career came to an end at the Paris Olympics on Thursday as another chapter closed on tennis's golden generation.
Distraught Italian boxer Angela Carini, showing signs of physical pain, shrugged off attempts by Khelif to shake her hand afterwards, collapsing to her knees and sobbing uncontrollably in the middle of the ring.