Summer McIntosh, the 18-year-old Canadian swimming star, rolled to victory Sunday in the women’s 400-meter individual medley, setting a world-championship record and winning her fourth individual gold medal of the event.

American star Katie Ledecky won her seventh world title in the women’s 800-meter freestyle on Saturday, fending off the challenges of Canadian sensation Summer McIntosh and Australia’s Lani Pallister.

McIntosh blitzed the field in the 400 IM with a time of 4:25.78, the world record holder coming home more than seven seconds ahead of joint silver medallists Jenna Forrester of Australia and Japan's Mio Narita. China's 12-year-old prodigy Yu Zidi finished just off the podium again having also come fourth in the 200 IM and 200 butterfly.