Thirteen-year-old Sky Brown earned a momentous skateboarding bronze to become Great Britain's youngest Olympic medallist as more success followed in sailing and boxing for Team GB on Wednesday.
Hannah Mills and Eilidh McIntyre clinched gold in the 470 class, making Mills the most successful female Olympic sailor of all-time after her gold in Rio five years ago and silver at London 2012.
Ben Whittaker also continued Team GB's impressive boxing campaign with a men's light-heavyweight silver medal after Frazer Clarke took bronze in the men's super-heavyweight division.
With six medals guaranteed in Tokyo this is Britain's most successful Olympics in the boxing ring since 1920, when just 12 nations took part.
Brown, born a month before the 2008 Olympics in Beijing, fell on her first two runs in the women's park skateboarding final before posting a score of 56.47 to make the podium.
The teenager replaces Sarah Hardcastle as Britain's youngest summer Games medal winner - the swimmer was aged 15 years and 113 days when she won silver and bronze in Los Angeles at the 1984 Olympics.
At 13 years and 23 days, Brown also breaks Margery Hinton's 93-year-old record as the country's youngest competitor and claims Team GB's first skateboarding medal into the bargain.
World champion Katarina Johnson-Thompson made a mixed start to her heptathlon campaign to sit third after two events and the British athlete is back in action later on Wednesday with the shot put and 200m.
Meanwhile, the GB women's hockey team saw their title defence come to an end as they lost 5-1 in their semi-final against the Netherlands in sweltering conditions at Oi Hockey Stadium.
They will have a chance to go for bronze against the losers of Argentina versus India.
Andrew Pozzi reached Thursday's men's 110m hurdles final, with his fourth-placed finish in the semi-finals enough to see the Briton through.
Alice Dearing, 24, made history as the first black swimmer to represent Britain at an Olympics, finishing 19th in the women's 10km marathon event.
American Sydney McLaughlin reeled in rival Dalilah Muhammad to win gold in a very fast women's 400m hurdles - and broke her own world record in the process.
Brown makes history in Tokyo
Brown beat the previous record of Team GB's youngest Olympic medal winner by more than two years while also becoming the youngest competitor at a summer Games for her country.
Hinton was 13 years and 44 days when she swam at the Amsterdam Games in 1928 and that landmark stood for almost a century.
Until Wednesday, that is, when Brown - 19 days younger - began her women's park skateboarding campaign at Ariake Urban Sports Park.
Had the Games not been postponed by a year, Brown would have lowered that summer record further, though figure skater Cecilia Colledge retains the overall accolade for Britain - she entered the 1932 Winter Olympics in Lake Placid aged 11.
Brown qualified for the final but fell during her opening two runs to set up a tense final attempt.
But the Japan-born teenager - who had a heavy fall in training last year that saw her fracture her skull, break her left arm and wrist and suffer lacerations to her heart and lungs - delivered a score of 56.47 to climb into the bronze-medal position.
"This is incredible. It feels unreal, I'm so happy to be here, I'm blessed," said Brown, who added she would now "hang out with friends and party".
"I was definitely bumped, I fell twice, that made the last run feel even better. All the girls are ripping it, it was insane, it was a super-sick final."
Japan's Sakura Yosozumi, 19, won gold with a best score of 60.09, while 12-year-old compatriot Kokona Hiraki claimed silver with 59.04.
Mills adds to medal haul
Britain's stellar Olympics continued on the water, with Mills and McIntyre's success taking the nation's sailing medal tally to five, of which three of those are gold.
The GB pair finished fifth in the 470 medal race, but their earlier performances meant it was enough to hold off silver medallists Poland and France in bronze.
Their celebrations were put on ice briefly after a protest was lodged by bronze-medallists France.
But 33-year-old Mills, one of Team GB's flag bearers at the opening ceremony, did not have to wait long to have her third Olympic medal confirmed.
McIntyre, meanwhile, follows in the footsteps of her father, Mike, who won gold in the star class at Seoul in 1988.
Earlier, Britain's Chris Grube and Luke Patience finished fifth overall in the men's 470.
Boxing success continues for Team GB
Whittaker said his ambitions before Tokyo 2020 were to claim Olympic success and become the mayor of Wolverhampton.
His ceremonial dreams are yet to be determined, but the 24-year-old returns home draped in Olympic silverware after being edged out of gold by Cuba's Arlen Lopez.
Whittaker lost the light-heavyweight final on a split decision as Lopez added the title to the middleweight gold he won at Rio 2016.
"You don't win silver, you lose gold," said an emotional Whittaker. "I'm very disappointed with myself, I didn't perform well. Of course, he's a class operator - two-time Olympic gold medallist now but I'm very disappointed. I feel like a failure.
"Wolverhampton's mayor, bless him, did a little video for me wishing me luck, he said that if I get the gold, I get the chain - I didn't get the gold so he can keep it for a bit."
Whittaker's silver came shortly after Clarke took a super-heavyweight bronze.
The 29-year-old was stopped in his semi-final against Uzbekistan's Bakhodir Jaloolov after a cut he suffered in the previous round reopened above his eye.
"It's not the fairytale that I wanted but I'm proud of myself," Clarke told BBC Sport. "I'm gutted I didn't do a little bit more but I'm an Olympic bronze medallist.
"I'm healthy and I've been to the Olympic Games. I can't ask for anything more."
Britain have already guaranteed two further medals, with Galal Yafai in the flyweight semi-finals on Thursday before Lauren Price's middleweight semi-final bout on Friday.
What is coming up?
Track Cycling: Jason Kenny gets under way in the men's sprint (from 07:30 BST)Climbing: Shauna Coxsey in the women's combined event (from 09:00 BST)Showjumping: Ben Maher, Harry Charles and Scott Brash are in the individual event (from 11:00 BST)
