Emma Snowsill claimed triathlon gold for Australia as she stormed to victory in Beijing on Monday.
The Commonwealth Games champion, 27, broke clear at the start of the 10k run and never looked like being caught as she won in one hour and 58.27 seconds.
Portugal's Vanessa Fernandes won silver and Australian Emma Moffatt the bronze.
British world champion Helen Tucker came 21st while Hollie Avil, who has been struggling with a stomach bug, withdrew during the 40k bike ride.
Tucker had been in contention at the changeover from bike to run, having been in the lead group for much of the race.
But Snowsill stormed clear and another breakaway group formed and Tucker struggled to match the pace.
"To come from a nation that's so strong in terms of triathlon, it's a fantastic feeling to finally bring home a gold medal"
The Welsh triathlete finished more than four minutes behind Snowsill but Avil, the 18-year-old national champion, could not finish the race because of the after effects of an illness at the weekend, which left her unable to eat.
"I have always told myself I would never not finish a race and it's hard to describe how I feel having to pull out," she said.
"When I was on the bike I was sick and every time I took on fluids I was sick again.
"But my aim has always been to compete at London 2012 and I've gained so much experience."
An eight-bike pile-up at the end of lap five dashed the hopes of Canada's Laura Groves and Russian Irina Abysova as riders careered over the barrier and into each other at the hairpin stadium turn.
But Snowsill powered on to victory and made up for the pain of missing out on selection for the team to compete at the last Olympics in Athens four years ago.
"I feel very proud and honoured to be an Australian with a gold medal around my neck at the Olympic Games," Snowsill said.
"I believe we came so close in Sydney and Athens that this makes up for those very close defeats.
"I don't feel any regret about not going to Athens, you move on and you deal with it.
"But to come from a nation that's so strong in terms of triathlon, it's a fantastic feeling to finally bring home a gold medal."
Tucker was hoping to add an Olympic medal to her World Championship win earlier this year.
But the 24-year-old from Bridgend suffered heartbreak in Beijing as she finished four-and-a-half minutes behind champion Snowsill.
"I'm a bit gutted but my legs didn't feel great," admitted Tucker.
"I didn't feel awesome on the bike but I stayed in a good position but I didn't have any legs when it came to the run, it felt hard.
"I know I should do better than that but I've had an awesome year so I can't really complain.
"This experience here in Beijing really makes me want to succeed at the London Olympics in 2012."
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