It has not been a year since global swimming's finest rocked La Defense Arena at the Paris Olympics but there is already anticipation of record-breaking thrills at the world championships in Singapore.The meet kicks off with a bang on Sunday as Canada's teen machine Summer McIntosh looks to claim a maiden 400-meter freestyle world title after obliterating Ariarne Titmus's world record at Canadian trials.Australia's Olympic champion Titmus is skipping the action at the World Aquatics Championships Arena but American icon Katie Ledecky, the Paris bronze medalist, is entered in the 400, an event she has won four times.