SHANGHAI » Michael Phelps registered a comfortable win in the 100-meter butterfly at the swimming world championships Saturday without Milorad Cavic or Ryan Lochte to challenge him.

Phelps used his usual strategy for his third gold of the championship: Touching third at the turn and pulling ahead in the second lap to finish in 50.71 seconds. Konrad Czerniak of Poland took the silver in 51.15 while another American, Tyler McGill, earned bronze in 51.26.

Cavic, who is still regaining his form following back surgery, didn’t advance from morning heats Friday. Lochte, who edged Phelps for gold in the 200 freestyle and 200 individual medley, wasn’t entered.

Meanwhile, American teenager Missy Franklin continued to impress at her breakout meet, and Rebecca Adlington won the 800 free to give Britain its first gold in the pool and a big boost going into next year’s London Olympics.

The 16-year-old Franklin won the first major individual gold of her career in the 200 backstroke, then came back an hour later and swam the anchor leg as the United States claimed gold in the 4×100 medley relay.

Franklin has three golds and five medals in all, having also set up the Americans’ victory in the 4×200 free relay two days ago, when she swam faster than Federica Pellegrini did in winning the individual 200.

"I totally made sure I came in here and left everything in the pool, and I did," Franklin said, flashing a wide smile that revealed a set of braces. "I’m thrilled."

Rebecca Soni set up the relay win with a solid breaststroke leg, and she also has three golds. It was the first time the Americans won this relay at worlds since 1998 in Perth, Australia.

Also, Cesar Cielo retained his title in the 50 free, adding to his gold in the 50 fly. Having been cleared of doping by the Court of Arbitration for Sport last week and allowed to compete in worlds, Cielo broke down into tears after his fly win Monday. This time he remained composed and waved his arms in celebration.

Dutch speedster Inge Dekker won the women’s 50 butterfly, a non-Olympic event, in 25.71.

Cavic posed the most serious threat to Phelps’ record eight gold medals at the 2008 Beijing Olympics, losing the 100 fly by a hundredth of a second in 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 trash talk beforehand. Then Phelps rallied over the last lap to break the world record set by Cavic in the semifinals, with the Serb settling for silver again, prompting an unusually large outburst of emotion from Phelps.

Phelps didn’t celebrate at all this time, even though it was his third consecutive world title in this event.

"I thought I was going to be a little bit faster," Phelps said. "In all, it’s been an OK week. There will be a lot of helpful things I can work on for next year."

Phelps has three golds, two silvers and a bronze with one more event to go — the 4×100 medley relay on the final night of competition Sunday.

In the 200 back, Franklin led from start to finish in 2:05.10 — the third fastest swim of all-time in this event. She finished nearly a second in front of silver medalist Belinda Hocking of Australia, while Sharon van Rouwendaal of the Netherlands took bronze, a massive 2.68 seconds behind.

Returning from a year off, Olympic and defending champion Kirsty Coventry of Zimbabwe failed to qualify for the final.

Adlington, the Olympic champion, traded the lead with Denmark’s Lotte Friis throughout the race and posted a narrow 800 victory in 8:17.51. Defending champion Friis took the silver in 8:18.20 and Kate Ziegler of the United States took bronze.

Adlington trailed Friis at the 750-meter mark, but dug deep to pull out the win.

"We’ve always raced against each other and it’s always been, ‘One does it one year, one does it the next year,’ but I hope to god it’s me next year," Adlington said. "All I was thinking was, ‘I get to lie on a beach for like 10 days. I get to go on holiday. Just put my head down, it doesn’t matter if I ache.’"

Cielo clocked 21.52 seconds — far off his world record of 20.91 set at the end of 2009 just before high-tech bodysuits were banned. Luca Dotto of Italy took silver in 21.90 and Olympic 100 free champion Alain Bernard got bronze in 21.92.

"Coming out of this world championship with two golds and a fourth place, I think is a better situation than what I imagined two weeks ago," said Cielo, who was fourth in the 100 free.