SHANGHAI -- Michael Phelps vs. Milorad Cavic Part III is off.
Phelps advanced in the preliminaries of the 100-meter butterfly Friday, posting the fifth-fastest time of 51.95 seconds. But Cavic, who had back surgery last July, failed to move on. The American-born Serb finished 18th at 52.67, missing the semifinals by two spots.
Cavic posed the most serious threat to Phelps' record eight gold medals at the 2008 Beijing Olympics, losing to the American in the 100 fly by a hundredth of a second, a finish so close that the video had to be reviewed down to the 10-thousandth of a second.
Their rematch at worlds two years ago in Rome was dramatic, too. Both swimmers traded talked trash beforehand, with Cavic offering to buy Phelps one of the high-tech bodysuits that led to 43 world records at that meet.
Then Phelps, in his supposedly inferior suit, rallied over the last lap to break the world record set by Cavic in the semifinals, with the Serb settling for silver again.
But Cavic arrived rusty in Shanghai, having been slowed by surgery for a herniated disk in his back. He only began diving off the starting block two months ago.
Cavic waved off reporters after his heat.
Asked about Cavic's failure to advance, Phelps smiled slightly.
"I'll be the first one to say we all have our ups and downs with competitions," he said. "It's kind of how it goes after a rough stretch of time and he's the kind of guy who's going to be there. He and I have had good races in the past and I'm sure we'll have another one again."
Phelps was sixth on the opening lap of his heat before finishing third, behind teammate Tyler McGill and Dunford.
"My upper body has been hurting more than my lower body," he said. "I've been sitting in my ice bath every day and trying to recover the legs as much as I can. One of the biggest things at a competition like this is really being able to recover as fast as you can."
McGill was the fastest qualifier in 51.76. Takuro Fujii of Japan was second at 51.82, followed by 32-year-old Aussie Geoff Huegill at 51.83.
Cesar Cielo of Brazil, American Nathan Adrian and George Bovell of Trinidad and Tobago tied for the fastest time in the 50 freestyle prelims.
Defending champion Cielo, Adrian and Bovell touched in 22.03 seconds.
"I think everyone was hiding their game," Cielo said. "I don't think anybody went as fast as they're going to be tonight."
Adam Brown of Britain was fourth at 22.08. Alain Bernard of France advanced in 10th. South Africa's Roland Schoeman, the 2005 champion, made the semifinals in 15th.
Adrian wants a better result after finishing sixth in the 100 free on Thursday.
"I'm just preparing for tonight, go 21-anything, get in there safely and then move on to try to swim fast tomorrow," he said.
A trio of big names failed to make the cut. Brent Hayden of Canada, silver medalist in the 100 free on Thursday, tied for 17th, one spot out of the semifinals. American Cullen Jones, the 2007 silver medalist, and a shocked Frederick Bousquet of France, second to Cielo two years ago, tied for 20th.
"I kind of played with fire," Bousquet said. "I was very behind at 25 and I said to myself, 'No problem, I'll pass them at the end,' but by saying that I was not creating the effort to do that."
Cielo finished fourth in the 100 free, won by James Magnussen of Australia. The Brazilian sobbed after winning the 50 butterfly on the meet's second day, having just been cleared of a doping offense by the Court for Arbitration of Sport.
"I'm happy with how my races are going so far," he said. "I'm overcoming something really hard to overcome."
Dunford finished seventh in the 50 fly and afterward expressed his opinion of the CAS decision with a thumbs-down gesture.
"It wasn't a personal attack on Cielo," he said, "it was just on a system that seems to have let swimming down."
Missy Franklin, the 16-year-old American making her worlds debut, was fastest in the 200 backstroke at 2 minutes, 7.71 seconds.
Franklin has won three medals so far, including a bronze in the 50 back on Thursday.
"I'm so excited to be at this meet," she said, her smile revealing her braces. "Getting that top 16 was definitely the goal, so to be back first is really, really great and I'm super happy with that."
Daryna Zevina of Ukraine was second at 2:08.35, followed by American Elizabeth Beisel, the bronze medalist in Rome, at 2:08.40.
Defending champion Kirsty Coventry of Zimbabwe advanced in seventh, having struggled in her earlier races in Shanghai.
"My events just feel really hard, which usually even if I'm a little bit down, they don't feel that hard," she said. "The preparation I had coming in wasn't the best, but there's nothing I can do about it now. I just have to try to have strategic races and hope that kind of gets me into finals."
Anastasia Zueva of Russia, second to Coventry two years ago, missed the semifinals by one spot a day after winning the 50 back.
Olympic champion Rebecca Adlington of Britain easily advanced in the 800 free at 8:22.27. Defending champion Lotte Friis of Denmark, the 1,500 free winner, was second at 8:23.07.
American Chloe Sutton was third at 8:27.72, followed by teammate Kate Ziegler at 8:28.28.
The United States had the top qualifying time in the men's 4x200 free relay, with David Walters, Conor Dwyer, Ricky Berens and Peter Vanderkaay timed in 7:08.84. Phelps and possibly Ryan Lochte, who had the morning off after his world-record win in the 200 individual medley, will join the team for the evening final.
Japan was second at 7:10.46, followed by France at 7:11.60.
In the women's 50 butterfly, Therese Alshammar led the way at 25.68. The Swede, who turns 34 next month, is trying to regain the world title she won in 2007.
Jeanette Ottesen of Denmark was second at 25.88. American Dana Vollmer, the 100 fly champion, was third at 25.98.
Vollmer is using the non-Olympic event as practice in building her speed for the 100.
"We were kind of approaching it as a good warmup for the relay and I'm really excited with that time," she said. "It's just a fun event for me to play with."
Defending champion Marieke Guehrer of Australia was 13th.