SHANGHAI -- Michael Phelps got off to a losing start at the world championships, and it wasn't his fault. He put his teammates in second place on the opening leg of the 4x100-meter freestyle relay. They just couldn't move up.
Phelps, kicking off the first of his seven events at the eight-day meet, led off a stunning bronze-medal showing in the relay Sunday at the Oriental Sports Center.
It was the first time since 2007 that the American men lost a relay of any kind at worlds or the Olympics.
"It's frustrating," he said. "It's not how we want to start it."
They were upset by the Australians, who got an opening leg split of 47.49 seconds from James Magnussen and went on to win in 3 minutes, 11.00 seconds. He was joined by Matthew Targett, Matthew Abood and anchor Eamon Sullivan.
"We knew we weren't going to be in the mix on paper," Sullivan said. "We knew we had the experience and the young ones to surprise people."
France took the silver in 3:11.14 and the U.S. team of Phelps, Garrett Weber-Gale, Jason Lezak and Nathan Adrian earned the bronze in 3:11.96.
Weber-Gale swam the slowest of the Americans, with his 100 split timed in 48.33.
"I feel sick about it. It's a huge disappointment to get bronze," he said. "It's pretty embarrassing for me to go slow like that and it's disappointing to feel like it was my fault that we did poorly."
Lezak, the 35-year-old whose sizzling anchor leg at the Beijing Olympics preserved Phelps' successful bid for eight golds, swam the Americans' second-slowest split of 48.15.
"You can't go in and have two guys swim great and two guys swim average and expect to win," he said. "Unfortunately, I was one of the average ones."
The Americans were 2½ seconds faster winning the gold at worlds in Rome two years ago.
"It's a good thing that it's not the Olympics," said Phelps, who swam 48.08 on his opening leg. "We have time to prepare and get ready and change some things."
Asked what needed changing, he replied, "Clearly need to be faster. That's the easiest thing."
Ryan Lochte, who swam in the morning heats, didn't return for the final. U.S. men's coach Eddie Reese defended the decision, saying, "He was third-best this morning."
"This wasn't a very good relay for us," Reese said. "Why? We call it human beings. We had splits that were not at all like we thought it would be."
The U.S. women's 4x100 free relay didn't win, either. Natalie Coughlin, 16-year-old rookie Missy Franklin, Jessica Hardy and Dana Vollmer claimed the silver after Vollmer was overtaken on the next-to-last lap by Femke Heemskerk of the Netherlands.
"I never like diving in and coming second," said Vollmer, who earlier set an American record of 56.47 as the fastest qualifier for Monday's 100 butterfly final. "The 100 fly felt so easy and this wasn't quite so easy."
The Dutch team of Inge Dekker, Ranomi Kromowidjojo, Marleen Veldhuis and Heemskerk defended their relay title in 3:33.96.
The Americans touched in 3:34.47, followed by Germany in 3:36.05.
In the other finals, Olympic champion Park Tae-hwan of South Korea showed he's back in top form by winning the 400 freestyle, while Italy's Federica Pellegrini took the women's race.
Park regained the lead midway through and pulled away over the last two laps to win the gold in 3:42.04, a distant 1.20 seconds in front of silver medalist Sun Yang.
Two years ago, Park failed to make the final in Rome.
"I (was) glad to swim in lane one, which allowed me to fully concentrate on my own tempo and not to get distracted from the competition," he said.
Defending champion and world record holder Paul Biedermann of Germany settled for third, 2.10 seconds behind. American Peter Vanderkaay was fourth.
"I'm really pleased with this time," Biedermann said. "It's the best I could do at the moment. I felt pretty bad during the race. ... I saw Park and I thought, 'Well this guy is away, don't look at him anymore, look at silver or bronze.' "
In the women's race, Pellegrini was fifth at the midpoint before surging into the lead one lap later and cruising to victory in 4:01.97.
Olympic champion Rebecca Adlington took the silver in 4:04.01, while Camille Muffat of France earned the bronze in 4:04.06.
"I knew I could have a race like this and it went perfectly," Pellegrini said. "This gold is different from the one two years ago. I approach races differently now -- I eat and sleep, I'm much calmer."
American Katie Hoff finished seventh in her first world meet since 2007.
"That little extra something special you need to win a race wasn't there," she said.
Cesar Cielo, the Brazilian cleared of doping by the Court of Arbitration for Sport three days ago, led the 50 free semifinals in 23.19, while 32-year-old Geoff Huegill of Australia was second to qualify for his first worlds final since 2003.
"I don't have any pressure or expectations on me," Huegill said. "The pressure is on the young guys to maintain their form and keep the old buggers at bay."
Alexander Dale Oen of Norway was fastest in the 100 breaststroke semifinals, maintaining his focus following the twin tragedies in his country that killed at least 93 people.
"Life is more than swimming," said Dale Oen, who grew teary-eyed when asked after morning heats about Friday's bombing in Oslo and shootings on a nearby island. "What's happening back home really puts things in perspective. It's been terrible. Terrible. The whole day has just been emotional."
Olympic champion Stephanie Rice of Australia led the 200 individual medley semifinals in 2:09.65, with defending champion and world record holder Arianna Kukors of the United States second. Ye Shiwen of China qualified third.
Olympic silver medalist Kirsty Coventry of Zimbabwe, who took last year off, failed to qualify in ninth.