Sun wins third straight 400m free title

China's Sun Yang celebrates after the men's 400m free style final of swimming at the 17th FINA World Championships in Budapest, Hungary, on July 23, 2017. Sun Yang won the gold medal with 3 minutes and 41.38 seconds. (Xinhua/Ding Xu)

Chinese swimming ace Sun Yang won his third straight title in men's 400m freestyle, while Sarah Sjostrom surprisingly broke women's 100m freestyle world record in the team relay event at the 17th FINA World Championships on Sunday.

On swimming's opening day in the Hungarian capital, Sun, ranked second in the heat, set himself on the leading position after 150 meters en route to his third straight champion after 2013 and 2015. It was also the first swimming gold medal at the tournament this year.

Sun clocked 3 minutes 41.38 seconds, the fastest time of the year. Australia's Mack Horton, Rio Olympics gold medalist, finished runner-up at 3:43.85. Gabriele Detti of Italy was placed third with 0.08 second behind.

Sun let off all his pressure by roaring and punching water when he saw the results. Forefinger in the air means that he is still the best swimmer around the world in the event.

"It was not about my opponent's lackluster performance. Maybe I just did better today, and training on some details recently has paid off," Sun talked about his morale-boosting victory.

Sun will also compete in 200m, 800m and 1500m frees at worlds, and he needs to adjust himself quickly before appearing in the 200m heat on Monday morning.

Swimming powerhouse United States kicked off a winning start as they bagged the remaining three golds on Sunday.

In women's 400m freestyle, Katie Ledecky broke the championships record for the second time in a single day, as her time of 3 minutes 58.34 seconds has bettered that of 3:59.06 in the heat.

Her teammate Leah Smith ranked second at 4:01.54. China's Li Bingjie, 15, tasted the bronze at 4:03.25 in her maiden World Championships appearance.

Li, regarding Ledecky as her idol, said that she felt both excited and nervous in the water.

"I felt excited because I have got a chance of competing with my idol. However, it was just my first World Championships, unavoidably, I felt a bit nervous," she said, adding that she was not totally satisfied with the result.

Team USA also snatched two golds in men's and women's 4x100m freestyle relay, but Sjostrom grabbed more spotlight even though the Swedish team only finished fifth in the women's event.

Sjostrom, on the first baton, took on 51.71 seconds to break Australian Cate Campbell's previous world record of 52.06 seconds set last July.

The Chinese team, made up of Zhu Menghui, Zhang Yufei, Wu Yue and Ai Yanhan, followed Sweden to finish sixth.

Britain's Adam Peaty, first in men's 100m breaststroke semifinals, was the other athlete that set a new championships record at 57.75 seconds on Sunday. Chinese swimmer Yan Zibei also made into the final.

Ye Shiwen, London Olympic Games champion, was shocked in women's 200m individual medley, as she failed to secure a final spot after finishing 15th in the semi-finals.