Elinor Barker became only the fourth Welsh woman to win an Olympic gold medal as she followed Owain Doull to cycling success on the track.
Barker, 21, was part of the Great Britain team that earned a world record-breaking victory in the team pursuit on Saturday night.
In doing so, she followed compatriots swimmer Irene Steer (1912), fellow cyclist Nicole Cooke (2008) and taekwondo ace Jade Jones (2012).
Barker also enabled Laura Trott became the first British woman to win three OIympic gold medals.
Barker, Laura Trott, Katie Archibald and Joanna Rowsell-Shand comfortably defeated the United States in 4min 10.236sec to retain the title Britain won in London four years ago.
Barker followed fellow Cardiff cyclist Owain Doull, who, a day before, also won an Olympic gold medal and broke the world record in the GB team pursuit squad in Rio.
“We are incredibly lucky that we’ve been able to pull it off on the day and go faster than we’ve ever gone before,” Barker said.
“We’ve had some incredibly training sessions and we broke the world record a couple of times in training which we managed to keep quite quiet as well.
“But we’ve also had some terrible training sessions as well so it’s all about how it goes on the day really.
“I was struggling a bit, it was a shame we couldn’t go that little bit faster and get under 4:10
“Owain Doull was in the same situation struggling at the back like me, so it must be a Welsh thing!”
Trott is now one of Britain’s most successful ever female Olympians and has the opportunity to move clear on her own when she bids for a fourth gold in the omnium on Monday and Tuesday.
Rowsell Shand now has two gold medals, having also been part of the triumphant pursuit team at London 2012, while Barker and Archibald win their first.
The United States and then Britain both broke the world record in the semi-finals to set up a potentially thrilling decider.
The American quartet of Sarah Hammer, Kelly Catlin, Chloe Dygert and Jennifer Valente made a flying start and were 0.394 seconds up after only 500m of the 4km distance, but then Britain turned on the turbos and were just 0.096 seconds down after 1km and 0.931 seconds ahead at the halfway mark.
When the Americans lost one rider and drifted to 1.4 seconds down with 1km to go, the British squad had all but wrapped up gold and attention turned to whether they could break the world record for the third time at these Games, which they did by a huge 1.9 seconds.