Lamont Marcell Jacobs won a stunning 100m Olympic gold to give Italy two athletics titles within a matter of minutes as a scorching day in Tokyo also brought records and a sit-in protest.
The blue riband sprint event had been wide open since the retirement of Jamaican great Usain Bolt, who had won it at the past three Games, and it was Jacobs who took his chance to win the sport's biggest prize with a European record of 9.80 seconds.
He became the first Italian to win it and leaped straight into the arms of compatriot Gianmarco Tamberi, who was still wildly celebrating his shared gold in the high jump.
The lively evening athletics session, held at a cooler time of day after temperatures at the track had earlier reached 40C, even delivered a world record as Venezuela's Yulimar Rojas won triple jump gold.
There was also a record in the pool, where Australian Emma McKeon became the first female swimmer to win seven medals at a single Games with two golds on Sunday, and Belgium, Brazil and Israel celebrated various firsts for their countries in the gymnastics.
It was heat of a different kind at the boxing, where French fighter Mourad Aliev staged a remarkable sit-in protest because he was angry at being disqualified.
And local patience is being tested after organisers said they were investigating athletes drinking alcohol in a park at the Olympic Village, the day after two Georgian silver medallists were told to leave the Games for taking a sightseeing trip in Tokyo, where Covid-19 cases are surging.
In tennis, Germany's Alexander Zverev was in sizzling form as he beat Russian Karen Khachanov in straight sets to take men's singles gold, while American Xander Schauffele clinched golf gold.
Meanwhile, hopes of seeing pre-Games favourite Simone Biles performing again in Tokyo were further dashed when the American withdrew from another final, to leave just one more event in which she is still entered.
China are top of the medal table with 23 golds, with the United States second on 20 and hosts Japan third with 17.
Joyous scenes light up Olympic stadium
There may be no fans at these Games but there was no shortage of emotion on day three of the athletics at the Olympic stadium.
In the 100m, with favourites failing to make the final of an event Bolt had dominated for so long, and world champion Christian Coleman absent from the Games, it was a wide open race.
And Jacobs, who only switched from the long jump in 2018, streaked clear to win in 9.80 seconds, 0.04 clear of American Fred Kerley. Canada's Andre de Grasse won a second successive Olympic bronze in third.
The Italian rushed over to Tamberi, who was still on the track celebrating his high jump success after he shared gold with Qatar's Mutaz Essa Barshim.
The pair ended level, having both cleared jumps of 2.37 metres, and having got a nod when they asked the official "can we have two golds?" rather then enduring a jump-off, they embraced joyfully before celebrating with their coaches.
It was a second gold for Qatar in as many days after weightlifter Fares Ibrahim Elbakh won the country's first ever on Saturday.
That gold-medal event followed the women's triple jump, in which Venezuela's Yulimar Rojas was ahead from the first jump and having guaranteed the gold medal, put in a world record leap of 15.67m, beating the previous mark set by Inessa Kravets in 1995 by 17cm.
In the morning's action, Chinese world champion Gong Lijiao won the women's shot put gold with a personal best of 20.58m.
New Zealand's Valerie Adams became the first woman to win medals at four Olympics in a single field event by claiming the bronze, with American Raven Saunders picking up silver.
More golds for McKeon & Dressel on final day of swimming
Australia's McKeon outsprinted the field to win the 50m freestyle before helping Australia win the women's 4x100m medley relay as she joined Michael Phelps, Mark Spitz and Matt Biondi as the only swimmers to win seven medals at a single Olympics.
"It is an honour because I know I've worked so hard for it," she said.
American Caeleb Dressel, meanwhile, powered to victory in the men's 50m freestyle and swam an inspired butterfly leg in the men's medley relay to finish with five gold medals.
It meant the United States finished top of the swimming medal table with 11 golds, with Australia second with nine - the highest number they have won at a Games. Great Britain, meanwhile, also shone in the pool, leaving with four golds in their record haul of eight medals in total.
Zverev wins tennis gold as Bencic misses out on double
German world number five Alexander Zverev won the biggest title of his career with victory over Russian Karen Khachanov in the men's singles final.
The 24-year-old became the first German man to win an Olympic singles gold with a 6-3 6-1 win in just 79 minutes.
Switzerland's Belinda Bencic, who won women's singles gold on Saturday, could not match that in the doubles as she and Viktorija Golubic were beaten 7-5 6-1 by Czech top seeds Barbora Krejcikova and Katerina Siniakova.
It was the country's first tennis gold medal as the Czech Republic, having previously won as Czechoslovakia in 1988.
Biles withdraws again as Whitlock wins gold
The individual apparatus finals got under way without American gymnast Simone Biles, who pulled out of Monday's floor final having already withdrawn from Sunday's vault and uneven bar competitions to focus on her mental health.
Her replacement in the vault final, compatriot Mykayla Skinner, took the silver with Brazilian Rebeca Andrade - the all-around silver medallist - becoming her country's first female gymnastics champion.
There was also a first for Belgium, with Nina Derwael sealing the uneven bars title to become the first woman from her country to win Olympic gymnastics gold.
In the men's floor final, Artem Dolgopyat won Israel's first Olympic gymnastics gold and only their second Olympic title in any sport after Gal Friedman's 2004 windsurfing win in Athens.
He finished level on points with Spain's Rayderley Zapata but won the tie-break with a higher difficulty score.
Britain's Max Whitlock retained his pommel horse title with a sublime performance.
Boxer protests against 'unfairness'
The big talking point in the boxing ring on day nine of the Games was the sit-in protest by France's Mourad Aliev.
Unhappy that he had been disqualified for excessive use of his head in round two of his +91kg quarter-final against Britain's Frazer Clarke, the 26-year-old spent 30 minutes sitting on the ring apron after the fight, then left the arena before returning to the same spot.
"I sat down to protest against the unfairness for me," said Aliev, who had kicked the canvas and remonstrated angrily when hearing he had been disqualified.
"I prepared for these Games for four years. I really wanted to fight against the injustice, so that was my way to show that I don't agree with that decision."
Schauffele wins golf gold 'for dad'
American Xander Schauffele clinched the Olympic men's golf gold medal on a nail-biting final day that ended with a seven-way play-off for the bronze medal.
It was an emotional victory for the 27-year-old, who had spoken before the Games about how his father and swing coach, Stefan, was a former German decathlete whose own ambitions of competing at an Olympics were ended when he was left blind in one eye after a car accident.
"I really wanted to win for my dad. I am sure he is crying somewhere right now. I kind of wanted this one more than any other," said Schauffele, who won by one stroke on 18 under par.
Slovakia's Rory Sabbatini closed with an Olympic record 10-under round of 61 to finish in silver at 17 under, while CT Pan of Chinese Taipei finally claimed bronze on the fourth extra hole.