Britain's Rebecca Adlington set a new world record as she clinched her second swimming gold medal in Beijing with victory in the 800m freestyle.
The 19-year-old, who won gold in the 400m freestyle on Monday, destroyed the rest of the field as she finished 2.12 seconds inside the previous world best.
Italy's Alessia Filippi claimed the silver while Lotte Friis of Denmark finished third.
Cassie Patton, the second Brit in the final, finished eighth.
Adlington became the first British woman to claim gold since Anita Lonsbrough in 1960 with her 400m freestyle victory, and success in the 800m freestyle makes her the most successful British swimmer of the last 100 years.
606: DEBATE
If that was not enough, she made more history by smashing swimming's longest-standing world record. The world 800m best set by Janet Evans of the United States was done so in 1989, the year Adlington was born.
Having set a new Olympic record in qualifying for the final, Adlington was favourite to emerge victorious.
She snatched victory with the last touch in winning her first medal at the Water Cube on Monday, but had no such problems on Saturday.
The first 100m saw Adlington pushed all the way by Camelia Alina Potec who, after 50m, turned in the lead.
By 200m the pair were clear of the field and soon Adlington began to pull away from the Romanian.
At the halfway mark, she was in a race all of her own and her rivals had no answer as she stayed under world record time for the entire race, eventually finishing six seconds ahead of her nearest rival.
"I absolutely can't believe that has happened. I knew when I touched I had won and that was a great thing because I was just going for gold," she said.
"I didn't expect that record at all. It has always been a goal of mine but I never really expected it at this moment in time.
"To do it now and to do that time, it hasn't sunk in yet.
"This is just everything I have ever dreamed of and I'm so glad the hard work has paid off."
Her success in winning two golds in Beijing equals the best performance by a British woman at a single Olympics, following Dame Kelly Holmes's 800m and 1500m victories in Athens four years ago.
And she feels her achievements in Beijing are just reward for the effort she has put in during training.
"There are times when you don't even want to drive home, you just sit on the side of the pool.
"You just have to push yourself. You are pushing your body every single session.
"It is so nice for it finally to pay off. But I will be back training in no time."
Meanwhile, Francesca Halsall failed to reach the 50m freestyle final after finishing seventh in her semi-final in a time of 24.80secs.
Britta Steffen, Marleen Veldhuis, Libby Trickett, Hinkelien Schreuder, Kara Joyce, Aleksandra Gerasimenya, Dara Torres and Cate Campbell all qualified for Sunday's final.
Halsall said "It's been great experience and I've learned a lot ahead of the London 2012. I've still got the relays to come and that's going to be close.
"I'm still young and I've got loads I can improve on."
~RS~q~RS~~RS~z~RS~08~RS~)