Jodie Stimpson saw off a fierce challenge from fellow Briton Helen Jenkins to win the second round of the ITU Triathlon World Series in Cape Town, South Africa.
Stimpson pulled away from former world champion Jenkins, 30, to add to her triumph in Auckland, New Zealand.
Gwen Jorgensen of the USA was third, leaving a very strong finish just too late to catch the leaders.
Stimpson said: "I had a stitch, but I just managed to hold on."
She added: "I tried to break [Jenkins] going into the last lap and then I couldn't, so I just sat behind and I gave it all I've got."
Jodie Stimpson: Post race interview
The 25-year-old finished second in the series to Wales' Non Stanford last year, and has taken an early stranglehold on this year's event.
Wales' Jenkins continued her successful return to international racing, having finished third in Auckland in her first event since the 2012 Olympics.
"I felt strong," she said. "I got back up to Jodie. I knew she was going to play a tactical game, but I knew I had to keep the pressure on because Gwen was coming up from behind.
"I kept pushing and I didn't have anything at the end, but I'm happy to be on the podium."
Tactics came to the fore in the cycling leg with Britain's Lucy Hall, 22, leading a dozen-strong breakaway group that left the rest with too big a gap in the running stage.
Afterwards, Stimpson acknowledged the help of her fellow Britons saying: "The British girls were pushing hard on the bike today. They were definitely strong out there."
1. Jodie Stimpson GBR 1,600
2. Helen Jenkins GBR 1,425
3. Anne Haug GER 1,282
4. Sarah Groff USA 1,219
5. Gwen Jorgensen USA 1,024
In the men's event on Sunday, Britain's Olympic bronze medallist Jonny Brownlee, 24, will resume his battle with Javier Gomez, 31, after admitting the Spaniard "destroyed" him in winning in Auckland.
Brownlee, who lost the 2013 title to Gomez in a sprint finish in London, was easily beaten but still finished a strong second ahead of Australia's Aaron Royle.
Older brother and Olympic champion Alistair, 26, missed Cape Town with a calf strain, but is expected to race the next round in Yokohama, Japan.
The men's race takes place at 14:00 BST on Sunday.