Hannah Miley fell short in her mission to win Great Britain's first medal of the 2012 Olympics when she was fifth in a 400 metres individual swimming medley race that saw the first long-course world record set by a woman since the ban on performance-enhancing suits.
Ye Shiwen, just 16, secured China's second gold of the session after Sun Yang's commanding 400m freestyle victory.
Ye, who won the 200m individual medley aged 15 at the World Championships in Shanghai last year, produced a superb freestyle to stretch away and touch in four minutes 28.43 seconds.
World champion Elizabeth Beisel was second with Ye's compatriot Xuanxu Li third.
For Miley, it was a disappointment although she was never really in the hunt for a medal. The 22-year-old had been strongly fancied to challenge after her breakthrough on the global stage last year when she was second in the World Championships in Shanghai.
Despite the Garioch swimmer's best efforts, and her customary superhuman effort, she touched two places outside the medals in 4mins 34.17secs.
Miley, coached by her father Patrick in a 25-metre pool in Inverurie, was disappointed but knew she could not have given any more.
She told BBC Sport: "I gave it absolutely everything I had. It was a real job getting in the final and it was who could recover quickest.
"I'm disappointed I couldn't get a medal but I couldn't have given it any more - that was absolutely everything I had.
"Apologies for anyone who had high expectations for me."