Chinese world champion Jiao Liuyang went one better than her Beijing silver medal to claim the women's 200m butterfly final on Wednesday.
Jiao, who turns 21 next week, set an Olympic record 2:04.06 to beat Spain's Mireia Belmonte Garcia and Natsumi Hoshi of Japan.
She was the runner-up to teammate Liu Zige in the event at the 2008 Beijing Olympics, but finished well in front this time in the London final.
Jiao admitted she almost gave up the sport after fitness and attitude issues.
"I thought about giving up, the most difficult time for me was in 2009," she said.
"I wasn't in my best condition, mentally I wasn't that strong and I didn't always agree with my coach, so I had to change my technique.
"Four years ago (in Beijing final) I tried to catch Liu Zige but I failed, this time I was able to catch her. That was the difference.
"At the world championships, I said if she (Liu Zige) failed, I would get the gold, if I failed she would get the gold."
Jiao said by missing out in Beijing she had redoubled her efforts in training.
"Maybe because I did not win four years ago, it made me more consistent in my training, it kept me going," she said.
Belmonte Garcia, a silver medallist behind Jiao at last year's Shanghai world championships, was emotional to receive the silver medal.
"I can't believe it. It was a very difficult race and I didn't think I could do it," she said.
Liu, who led after the first 50m and was second at halfway, faded to finish eighth, a far cry from her gold medal-winning exploits in Beijing.
"I feel really disappointed. I didn't expect the result would be this bad," Liu said."I lost probably because I didn't practise well."