Anastasia Zueva claimed the women's 50m backstroke world record here on Wednesday, winning her World Championship semi-final in 27.38sec just minutes after Daniela Samulski had lowered the mark to 27.39. Germany's Samulski, swimming in the first semi, bettered the mark of 27.61 that she set in Berlin on June 26. But Zueva - who earlier this week set a new mark for the 100m backstroke before seeing it bettered on Tuesday by Briton Gemma Spofforth - responded with an effort that took the mark one-hundredth of a second lower. In all, five of the qualifiers for Thursday's 50m back final were faster than the record Samulski had established in June. Australia's Sophie Eddington was the third-fastest qualifier in 27.51, followed by Aleksandra Gerasimenya of Belarus (27.57) and China's Zhao Jing (27.59). 