BARCELONA — American teenager Katie Ledecky stormed to gold in the 400 meters freestyle at the World Championships here Sunday, becoming only the second woman after Italy's Federica Pellegrini to break four minutes. The 16-year-old Ledecky, gold medalist at 800 meters at last year's London Olympics, was on course to break Pellegrini's world record of 3:59.15 but slipped off the pace in the final 100 meters to finish in a still-blistering time of 3:59.82. Spain's Melanie Costa Schmid lifted the home support inside the hilltop Palau Sant Jordi by taking silver in 4:02.47 and Lauren Boyle of New Zealand was third in 4:03.89. Olympic champion Camille Muffat of France finished a disappointing seventh. Earlier, China's Sun Yang won the men's 400m freestyle gold with Kosuke Hagino of Japan in second and Connor Jaeger of the USA finishing third. Sun, 21, added the world title to the Olympic crown he claimed a year ago, and just as he did in the London 2012 final, Yang dominated from early on in Barcelona. The Chinese clocked 3min 41.59sec to claim the world title, finishing more than three seconds ahead of Hagino, who swam 3:44.82, while Jaeger finished in 3:44.85. At the halfway stage, Sun was on track to break Paul Biedermann's world record of 3:40.07, set four years ago at the Rome world championships, but the German ultimately holds on to the mark set using the now-banned high-tech suits. Chinese diver Qiu Bo made amends for the disappointment of missing out on Olympic gold last year to retain his world title in the men's 10m platform final. Qiu produced a near flawless display to finish well clear on 581 points with American Olympic champion David Boudia in second on 517.40 points and Germany's Sascha Klein back in third on 508.55 points. However, there was disappointment for Britain's Tom Daley as he was hampered by a torn tricep and could finish only sixth. It was sweet revenge for Qiu, who was surprisingly edged off the top of the podium in London by Boudia, as his victory meant China finished the diving meet with nine out of a possible 10 golds. Boudia was powerless to stop Qiu's march to gold despite leading for the first two rounds, but was still solid throughout as he picked up a second consecutive world championship silver medal. And he admitted that his eye may have been taken off the ball slightly since success in London. Russia underlined its total dominance in the synchronized swimming Saturday by completing a sweep of all seven gold medals with victory in the free combination team event. After winning all seven titles at the previous world championships in Shanghai two years ago and six out of seven at both Montreal in 2007 and Rome in 2009, the 10-strong Russian team wowed spectators at the Palau Sant Jordi with a typically acrobatic routine to amass a points total of 97.060. Spain got the home supporters rocking with a rousing Elvis Presley-themed routine to take silver with 94.620 and Ukraine clinched bronze ahead of Japan with 92.020. — Agencies