SHANGHAI -- The sprinters took over the pool at the world championships Saturday morning, with American Jessica Hardy the fastest qualifier in two events.
Her teammates, Michael Phelps and Ryan Lochte, who have combined to win eight of their team's 18 pool swimming medals, both had the morning off.
Phelps will swim his final individual event of the eight-day meet Saturday night in the 100 butterfly. Lochte wraps up in the 400 individual medley Sunday, when both he and Phelps are likely to be on the U.S. squad for the 4x100 medley relay.
Hardy and Therese Alshammar of Sweden tied for the leading time in the 50-meter freestyle preliminaries before Hardy returned to top the 50 breaststroke heats.
"It's been hard all week just sitting there because I've really wanted to race," Hardy said. "I was really giddy with excitement this morning. I didn't know what to expect because I sometimes don't always like to do well in doubles, but I'm really happy."
Hardy and Alshammar swam next to each other in the same heat, with both stopping the clock at 24.82 seconds. Alshammar, who turns 34 next month, is seeking her first world title after taking silver two years ago in Rome and in 2007.
Aliaksandra Herasimenia of Belarus, who tied for gold in the 100 free on Friday, was third at 24.85.
Also advancing to the evening semifinals were Dutch teammates Marleen Veldhuis and Ranomi Kromowidjojo, American Amanda Weir, and Denmark's Jeanette Ottesen, who shared the 100 free gold with Herasimenia.
Germany's Britta Steffen didn't defend her 50 free title after posting slow times in her previous events and dropping out of the meet.
Hardy's time of 30.20 made her the top qualifier for the 50 breast, in which she holds the world record and won the 2007 world title.
Hardy is working her way back after serving a one-year ban that cost her a spot on the U.S. team for the 2008 Beijing Olympics. The Court of Arbitration for Sport accepted that she was not at fault for taking a contaminated dietary supplement, but she still was penalized.
"Possibilities are endless," she said. "I'm really excited and really, really grateful."
Defending champion Yuliya Efimova of Russia and American Rebecca Soni, who swept the 100 and 200 breast here, tied for second at 30.72.
"The field is really tough, with Hardy in there, with Yuliya, so I'm not expecting anything," Soni said. "It's been a great run so far and now it's just the fun stuff -- the relay and the 50."
Leisel Jones of Australia, the silver medalist in 2007, was fourth at 30.93.
Hardy will have less than 45 minutes between evening semifinals.
"I definitely held back in both my races this morning," she said. "You want to make sure you feel good and I did."
The United States easily advanced in the women's 4x100 medley relay heats with the top time of 3:56.95 by Elizabeth Pelton, Soni, Christine Magnuson and Weir.
Russia was second at 3:59.08, followed by defending champion China at 3:59.44.
Australia finished fourth after adjusting its lineup when Emily Seebohm couldn't swim because of the flu. Alicia Coutts and Jones were brought in to join Stephanie Rice and Merindah Dingjan, and ensure the Aussies got a spot in the evening final.
"I was warned late last night that I could possibly be swimming this morning so I prepared myself, got up early, had breakfast," Coutts said. "It was good to get out there and do a swim, especially because I hadn't done the fly since the beginning of the week."
China's Sun Yang swam the fastest time in the 1,500 free at 14:48.13, putting himself in position to make a run at Grant Hackett's 10-year-old world record in Sunday's final. The four-time world champion from Australia set the mark of 14:34.56 at the 2001 worlds in Japan. Sun already won the 800 free here.
"Sun has definitely taken a huge leap toward taking down that world record for either this year or next year," defending champion Ous Mellouli of Tunisia said. "Obviously he's at home, he's pumped up and he's ready. You can tell. This is probably his best shot at it."
Mellouli finished 15th and didn't advance after being fourth in the 800.
"Definitely these are my worst world championships so far. Even not being in 100 percent shape, I assured two finals, so I was kind of mentally tough," he said. "I got to get back to work."
Hungary's Gergo Kis, the bronze medalist in the 800, was second at 14:52.72.
American Peter Vanderkaay was third at 14:54.99 and teammate Chad La Tourette fourth. Ryan Cochrane of Canada, second in the 800, was fifth.
In the men's 50 backstroke, Gerhard Zandberg of South Africa led the way at 24.72. He won the bronze in 2009 and was the world champion in 2007.
Camille Lacourt of France, who tied for gold in the 100 back, was second at 25.03. Helge Meeuw of Germany was third at 24.04.
Americans Nick Thoman and David Plummer tied for eighth at 25.22. Britain's Liam Tancock advanced in a tie for 10th with Aristeidis Grigoriadis of Greece.
"I'm more of a look into the future kind of guy, then look into the past," Tancock said about being the defending champion. "I'll have plenty of time when I retire to look at what I've done in this sport. I enjoy each race as it comes."