Jiao Liuyang of China sped to gold in the women's 200m butterfly on Wednesday.
Jiao, the Bejing silver medalist at the age of 16, went one better this time to win in 2 minutes, 4.06 seconds, a new Olympic record.
"It was my strategy to accelerate in the last 50, as in the semifinal I swam too fast in the first half and it made me really tired for the second half," Jiao said.
"I am really happy but I still need to put more effort in training as it was not an easy win."
Spain's Mireia Belmonte Garcia won a surprise silver in 2:05.28, while Japan's Natsumi Hoshi took the bronze in 2.05.48.
"I felt nervous but strong. I feel like I've achieved a dream," Belmonte Garcia said.
"I thought nothing as I left the pool. My mind went blank."
It was China's fourth gold in the pool.
