RIO DE JANEIRO, Sept. 8 (Xinhua) -- China's Song Lingling broke her own world record to win gold in the women's 100m backstroke - S6 final on Thursday.

Song finished in 1 minute 21.43 seconds to beat her previous record of 1:24.66 at the Olympic Aquatics Stadium.

China's Lu Dong took silver, 22 hundredths of a second behind her compatriot, with Ukraine's Oksana Khrul claiming bronze in 1:26.82.

"I am very happy to win a gold medal. I never thought this was going to happen," Song said. "I did not start the race so fast, but then I sped up and I won. Of course, now I will celebrate having my gold medal."

Song, 20, suffers from impairment to her legs as a result of polio.