American Rebecca Soni broke the women\'s 200m breaststroke world record with a time of 2min 20.00sec in the semi-finals at the London Olympics on Wednesday. Olympic champion Soni reached the final in emphatic style as she bettered the previous world record of 2:20.12, set by Canadian Annamay Pierse in July 2009 at the world championships in Rome. It was the second world mark to fall on Wednesday night, after Hungarian Daniel Gyurta\'s record-breaking swim in winning gold in the men\'s 200m breaststroke.