Beth Shriever won BMX racing Olympic gold minutes after Great Britain teammate Kye Whyte secured silver in the men’s event.
Shriever had looked the class of the field in qualifying and delivered in the final.
She led from the first bend, holding off a late charge from defending champion Mariana Pajon of Colombia down the final straight.
Shriever, 22, needed crowdfunding to be able to go to Japan but she was lifted into the air by Whyte as the pair celebrated their historic achievements in Tokyo.
"I’m in shock. To even be here is an achievement in itself," Shriever told BBC. "To make the final is an achievement in itself. To win a medal – honestly I’m so over the moon. It just means so much.
"I’m so grateful for the support. Everyone waking up at home. I’m just overwhelmed."
Former teaching assistant Shriever paid tribute to British Cycling and coach Stephen Park after claiming gold.
She said: “I was working part-time and training on the side as well. I never thought I’d even be here so to have British Cycling believe in me and give me the opportunity to be a full-time athlete and see my potential I’m so grateful for.
“Without them I wouldn’t be in the position I am today. I’ve been able to train every day and had a great support group, my family and friends around me. I wouldn’t be here if I wasn’t doing this full-time in training.
“I was a teaching assistant at a primary school back in Essex working with three and four year olds. I was doing that for two years and then Sparky saw my potential at British Cycling, got me on there and I’m now at Manchester full-time.”
Former Oasis frontman Liam Gallagher paid tribute to the new Olympic champion, posting on Twitter: “Bethany Shriever what a ledge well done LG x”.
Shriever’s gold came just moments after Whyte had broken Britain’s BMX medal duck in the men’s event.
The 21-year-old from Peckham had shown great pace in qualifying but, as in Thursday’s heats, found himself needing to recover from slow starts in all but the final run.
But come the medal race he had no such issues as he made it in to the first corner in second place behind Kimmann.
The two crossed the line with a healthy margin after a late crash for Frenchman Romain Mahieu split the field, with Colombian Carlos Ramirez Yepes taking bronze.
“With the way I was riding today, I was obviously catching people but I thought I would have to do the same in the final and it’s very tiring,” Whyte said.
“I just came out of the gate, and I didn’t expect it but in the back of my head I kept telling myself I was going to get a medal.
“I didn’t deserve it any more than any of the other riders but I put my head to it and I got a medal.”
Whyte began his celebrations by a TV screen showing a link to the party taking place at the Peckham BMX Club – the place where his father was a coach, his mother the secretary, and his path to this moment began.