Yao, 19, pipped defending champion and compatriot Huang Huidan by a razor-thin 0.067 points in the women's uneven bars for her first world crown, which follows her four-gold rampage at the Asian Games last month.
"Nothing happened. I was just very happy," explained Yao later.
She also had to console her defeated teammate.
"When I saw Huang Huidan crying, I really thought that she did better than me."
Liu, 20, stunned Olympic and world champion Arthur Nabarrete Zanetti of Brazil on the men's rings in a show of strength that lifted him from last year's fourth place.
Liu said his performance was not ‘text book’, as some reports had admiringly described it, as his young age meant he still had much to learn.
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