Ekaterina Andreevna Bychkova (Russian: Екатерина Андреевна Бычкова, born June 5, 1985) is a professional tennis player, born in Moscow, Russia. She is most famous for defeating defending champion Svetlana Kuznetsova in the first round of the 2005 US Open. She defeated her by a score of 6–3, 6–2. It was the first time a defending US Open Champion had lost in the first round. The win didn't last for long; Bychkova lost in the second round to Ivana Lisjak.