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.
Chebet -- nicknamed "the smiling assassin" -- bided her time before accelerating past compatriot Faith Kipyegon down the home straight to take gold in 14min 28.56sec at the Stade de France.
Hosts France will play an Olympic men's football final for the first time in 40 years after beating Egypt 3-1 in extra time at the Lyon stadium on Monday and will face Spain for the gold medal.
It was on these tracks more than a decade ago that Hassan, a young asylum-seeker from Ethiopia, embarked on a journey that would lead to history at the Tokyo Olympics and make her a top medal contender in Paris.
In cities across Taiwan, from Wang's home in the capital Taipei to southern Kaohsiung, and Lee's hometown on the island of Kinmen just off the coast of China, public screens were set up that lured thousands of fans.
The 27-year-old American catapulted himself into a new level of stardom on Sunday after ending the USA's 20-year wait for a gold medal in the Olympics' most coveted title.
Artistic gymnastics marks its final day with the spotlight on two women's events – the balance beam and floor exercise finals featuring American Simone Biles.
South Sudan coach Royal Ivey was highly critical of the officiating as his side's Olympic basketball dreams came to an end as they failed to qualify for the men's quarter-finals in a heartbreaking loss to Serbia.
"I feel honoured just to be an ambassador for my country," Alfred told reporters. "Not many people know about Saint Lucia. Sometimes I can be in an Uber and they ask me where I'm from... and they'll be like 'Where's Saint Lucia?'"
The 17-year-old swimmer did it in an Olympic record time of two minutes 06.56 seconds, taking down the 2016 record of 2:06.58 set by Hungary's Katinka Hosszu, to complete a medley double after winning the 400 last Monday.
Her victory comes after her brother, Finn Florijn, won gold in quadruple sculls earlier this week while their father, Ronald Florijn, is a two-time Olympic champion –- at the 1988 Seoul Olympics and at the 1996 Atlanta Games.