AP Sports Writer
BARCELONA, Spain (AP) -- Olympic champion Sun Yang comfortably led the 400-meter freestyle heats on the opening day of the traditional pool events at the swimming world championships Sunday.
For Chinese teammate Ye Shiwen, it was a different story.
Ye, the surprise winner of both women's individual medleys at last year's London Olympics as a 16-year-old, had to settle for second in the 200 IM prelims behind Katinka Hosszu of Hungary.
Hosszu clocked 2 minutes, 8.45 seconds -- a nearly unheard of time for heats and one that would have earned her a bronze medal in London. Ye, swimming in the next lane, touched in 2:10.20.
Sun led the 400 in 3:44.67 and Ryan Cochrane of Canada was second with 3:45.74. Olympic silver medalist Park Tae-hwan skipped the meet.
Also, American teenager Katie Ledecky led the women's 400 free heats by a large margin, touching in 4:03.05.
And the United States led both the men's and women's 4x100 free relay heats.
Four finals were scheduled for later on Day 1, in the men's and women's 400 free and the men's and women's 4x100 free relays.
The women's 200 IM final isn't until Monday.
Hosszu has been hailed as a top medal contender since winning the 400 IM and taking two bronzes at the 2009 worlds in Rome. But she failed to bring home any hardware from both the 2011 championships in Shanghai and the London Games.
If her prelim swim was any indication, that should change here.
"I was very surprised," Hosszu said. "That's a really good sign for me because I can usually feel about where I rank. I thought it was like 2:10 or 2:11."
Ye's Olympic-winning time of 2:07.57 appears in reach for Hosszu, or even the world record of 2:06.15 set by American Ariana Kukors in 2009 at the height of rubberized suit era.
"I definitely feel like I can go faster," Hosszu said. "In the final there will be eight swimmers and we all want to win. We will see who is the fastest."
Ye did not appear concerned.
"That was pretty good for the morning," she said through a translator. "I just followed what my coach told me to do. He said if I finished in the top two, that was good enough.
"The most important thing is the first 100," Ye added. "The breaststroke is most important. I cannot get too far behind in the breaststroke. I'm very confident in my freestyle."
In his event, Sun was more than four seconds off the time he won with in London.
"I tried to get a good place in the final," he said. "I saw that the field was very good and I had to go hard to get a place in the final."
In the women's 400 free, Ledecky was under world-record pace early on.
"Oh really?" she said. "I wanted to take the prelims really seriously so I would make it back to finals in a good spot. I'm excited to race the world's best tonight."
Ledecky burst onto the scene a year ago as a 15-year-old when she won the 800 free in London with the second fastest time in history. Then at the U.S. trials last month, she became the first American woman to qualify for the worlds in the 200, 400, 800 and 1,500 free.
Is she worried about taking on too much?
"No. Not at all," she said. "I've put in the preparation this year so I think I'm up for it."
Melanie Costa of Spain qualified second behind Ledecky, a distant 1.15 seconds behind, while Olympic champion Camille Muffat of France got through in sixth.
In other prelims, Olympic and defending world champion Dana Vollmer of the United States led the women's 100 fly in 57.22.
Olympic silver medalist Christian Sprenger of Australia topped the men's 100 breast in 59.53 while London champion and world-record holder Cameron van der Burgh of South Africa advanced in seventh. Alex Dale Oen, the Norwegian who won this event at the last worlds, died of a heart attack last year.
And in a non-Olympic event, 33-year-old Roland Schoeman of South Africa led the 50 fly in 23.02. Local favorite Rafael Munoz of Spain qualified second in 23.17. Defending champion Cesar Cielo of Brazil made the semifinals in eighth.
Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.