Team GB's gold medal tally rose to 16 after horse riding star Charlotte Dujardin took first place in the Olympic individual dressage.
The 31-year-old successfully defended her title with a sizzling performance, putting her level with cyclist Laura Trott on three Olympic golds.
Dujardin won with the brilliant Valegro on an Olympic record grand prix freestyle score of 93.857%, as they obliterated the field.
She told the BBC after her win: "It means the absolute world to me.
"Today I felt a huge amount of pressure and expectation and it could be one of the last rides on Valegro.
"It's a really emotional time and I'm so happy and I just really really want to thank everybody behind the scenes who's made this possible."
Among the Deodoro crowd was Dujardin's fiance Dean Golding, who sported a sign on his T-shirt saying: ''Can we get married now?''
In response Dujardin, who has been engaged for "a long time" said: "There was competition after competition after London, but I will make sure it happens this time.''
Meanwhile, Mark Cavendish bagged his elusive Olympic medal by winning silver in the Omnium at the velodrome in Rio.
The 31-year-old Manxman, 30 times a Tour de France stage winner, was third entering into the second day of racing for the last two disciplines of the event.
On Monday night Cavendish stormed home in the flying lap with a time of 12.793 seconds and after the points race finished second overall to take the silver medal.
He told the BBC he was "super happy" with his achievement, adding: "I would have liked gold, but I have got my Olympic medal."
He thanked all the team behind the British Cycling team and said: "Without those guys I wouldn't be stood on the podium today."
But a mid-race crash, which appeared to be of Cavendish's own making, means he may yet face a protest from rivals or a sanction from race officials which could deny him the podium spot.
Cavendish hugged his family and picked up his baby son after the race before returning to the track.
He later said: "I've had such great support. We've rushed the medals here as Great Britain. We have got the best bike riders in the world but what's been forgotten the past few days is we have the best staff behind us.
"It's a massive team and one that really wants to win and it's quite emotional, especially for me. I needed those people in what was my third ever international omnium."
His silver medal comes as Trott looks set to take gold in the women's Omnium on Tuesday in a bid to become the first female athlete from Britain to win four Olympic gold medals.
Earlier on Monday, British hammer thrower Sophie Hitchon broke her own national record and landed bronze with the last throw of the competition
The former ballet dancer launched the hammer out to 74.54 metres to move from sixth place to third and become the first British woman to win an Olympic medal in the discipline.
The 25-year-old from Burnley is the first Briton to win an Olympic hammer medal since 1924, and only squeezed into the final as the 11th of 12 qualifiers.
She said: "I can believe it a little bit because training has been going so well but to do it in competition is a little bit different. I knew it was there if I pulled it together and it is a bit special.
"I knew straight away when I let go. I turned around and my coach (Tore Gustafsson) was like, 'yeah'. I know if he likes it, it's going far. When it landed I was a bit like, 'is it, is it?' I didn't want to look stupid because I'd been cheering. It came off and I was thrilled."