Great Britain won the gold medal in the inaugural mixed 4x100 metre medley relay in a world-record time of 3 min 37.58 sec at the Tokyo 2020 Olympic Games.
Britain's total of four swimming golds in Tokyo is their best return in 113 years.
Britain, the fastest qualifiers, had European champion Kathleen Dawson swim the backstroke leg; two-time reigning Olympic champion and world-record holder Adam Peaty on breaststroke; James Guy, a member of the Olympic gold medal-winning 4×200m freestyle relay team on butterfly; and 100m freestyle Olympic finalist Anna Hopkin, replacing Freya Anderson from qualifying, on the anchor leg.
Dawson was sixth after the backstroke leg, as the men of the United States, Italy and China surged ahead, but Peaty slashed the deficit and pulled Britain into fourth after the breaststroke.
Peaty handed over to Guy, who catapulted Britain into the lead with a thrilling butterfly leg on which he moved past China's gold medallist Zhang Yufei to give Hopkin enough space to fend off a late challenge from Australia's 100m freestyle champion Emma KcKeon and China's Yang Junxuan, a member of the gold medal-winning women's 4x200m freestyle relay.
Guy withdrew from his individual butterfly event to focus on the relay and was happy the risk paid off.
"It's my fastest split ever by 0.5 seconds. Gold medal, world record, you can't beat that, especially when it's for the team.
"I was quite upset [about pulling out of the 100m butterfly] -- I cried again, obviously -- but it has paid off and it was worth it to go and do that time.
"To do this with one of my best mates in Adam and the two girls, we're all northerners -- it's amazing!"
In track and field, Team GB star Dina Asher-Smith failed to qualify for the women's 100-meter final on Saturday and immediately pulled out of the 200m, revealing a hamstring injury in the build up to Tokyo 2020.
Asher-Smith improved on the 11.07 seconds she recorded in the heats on Friday but it wasn't enough to secure a top eight finish and progress to the final.
After the race, She revealed to the BBC that she tore her hamstring "pretty bad" during the Olympic trials in June, which saw her miss meets at both Stockholm and Gateshead.
Great Britain's Daryll Neita placed eighth in the 100m final after she secured a qualifying spot in the third semifinal. Jamaica took a sweep of the medals, with Elaine Thompson-Herah breaking the Olympic record to win gold.
There will also be three British women in the 800m final after Keely Hodgkinson, Alex Bell and Jemma Reekie all qualified for the event.
Elsewhere, Alex Yee delivered a superb final leg as Great Britain won the inaugural Olympic Games triathlon mixed relay gold medal on Saturday.
Jess Learmonth led Britain out, while Georgia Taylor-Brown and anchor leg Yee, who both won silver in the individual events, completed the impressive all-round display.
The victory takes Britain's medal tally in triathlon to eight, including three golds, since the event was introduced to the Olympics in 2000.
It was an emotional triumph for Jonny Brownlee, who won individual bronze and silver in 2012 and 2016 and finally bagged a gold to enable him to share bragging rights with double individual champion and big brother Alistair.
"The Olympics is complete -- it feels absolutely amazing," Brownlee said.
"My third Olympics and I can finally walk away with gold.
"The Olympics is always special but to do it as a team is absolutely amazing."
Emma Wilson took bronze in the women's windsurfing, finishing behind Lu Yunxiu who took gold and Chareline Picon in second.
Wilson had impressed with her course management this week, and judged the wind perfectly on the day.
"I tried so hard in that race, and kept going and going," Wilson said on the BBC. "Obviously I wanted to win, so any medal is amazing. I'm super happy.
"I gave it everything and had no fear. I've dreamt of this since I was a little kid, watching Usain Bolt and Jessica Ennis. So it's just amazing.
"I'm so sick of coming fourth, it doesn't get much worse than that. I didn't feel too much pressure and I just tried to keep smiling.
"I didn't believe I'd be the first to get a medal but it's cool and hopefully other people will get one too."
Wilson comes from impressive Olympic stock, with her mum Penny competing at the 1992 Games in Barcelona and again in Atlanta four years later.
In boxing, Karriss Artingstall won bronze after losing her featherweight semi-final bought to Japan's Sena Irie. The 26-year-old was edged out on a 3-2 split decision.
"I knew it was close, I started slowly and catching up is a nightmare. Ask any boxer in the world, dropping that first round and trying to catch up is absolutely horrible," Artingstall said.
"I tried my best and managed to pick it back up in the second and I know not many girls can match my fitness so I thought I'll stick it on her chest -- I was getting caught here and there -- and I was doing well. But I am not going to moan about the decision.
"I have been on the GB programme for two-and-a-half years and I am a World and Olympic medallist. Come Paris , I will be taking that title."
Meanwhile, Lauren Price is guaranteed at least an Olympic bronze after beating Panama's Atheyna Bylon in the middleweight quarter-finals.
The 27-year-old, who is top seed in the competition, will take on the Netherland's Nouchka Fontijn in the semi-finals.
However, Luke McCormack was knocked out of the men's lightweight boxing competition by Cuba's two-time world champion Andy Cruz in the last 16.
In golf, Great Britain's Paul Casey and Tommy Fleetwood head into the final round in medal contention after a low-scoring day at the Kasumigaseki Country Club.
Casey sits in bronze-medal place at 12 under after he carded a superb 66 to rocket up the leaderboard. The 44-year-old is two shots back from leader America's Xander Schauffele and one shot behind second-place home favourite Hideki Matsuyama.
Fleetwood recorded the second-best score of the day, carding a third-round 63 to move to joint-ninth place at 10 under.
Elsewhere, GB women's hockey secured a quarter-final spot after beating Ireland 2-0 in their final pool match.
Susannah Townsend and Hannah Martin were on the scoresheet as Britain look to defend their gold from Rio 2016.
However, there was disappointment for GB women's rugby sevens as they were denied a bronze by a strong Fiji side, losing 21-12.
Fiji led from the off with Alowesi Nakoci scoring twice with no reply but a late try in the first-half from Megan Jones gave Britain hope going into the final seven minutes.
Despite another last-minute score from Jones, Fiji extended their lead in the second-half, putting in a dominant performance to take the third place spot.
"You can probably tell by all our faces we are absolutely gutted," GB's Jasmine Joyce said to the BBC.
"As a squad, we're Team GB, we are three different nations, and we have only been together for four-five months.
"Six months ago none of us had anything: we didn't have jobs, nothing, so to come out here and come fourth place and push New Zealand right to the end, beat USA in the quarter-final and unfortunately lost to Fiji -- who are a very good side -- unfortunately [New Zealand] were the better team today.
"I can't be prouder of the girls and we've definitely put our programme in a better place. We can call ourselves Olympians."
Meanwhile, Helen Glover, the first British mother to row at an Olympic Games, returned home after narrowly missing out on a medal with Polly Swan in the women's pair on Thursday.
The 35-year-old posted a heartwarming video on twitter of when she reunited with her three children at the airport.
Information from Reuters contributed to this report.