BARCELONA, Spain >> Missy Franklin stands alone.

Franklin claimed her record sixth gold medal of the world championships Sunday night, swimming the leadoff leg for the Americans in the 400-meter medley relay. She gave the U.S. a slight lead, and her teammates — Jessica Hardy, Dana Vollmer and Megan Romano — made it look easy from there. The winning time was 3 minutes, 53.23 seconds, nearly two seconds ahead of runner-up Australia.

The 18-year-old Franklin became the winningest female swimmer ever at the worlds and improved on her performance at the London Olympics, where she was one of the biggest stars with four golds and a bronze.

She eclipsed the women’s record that had had been shared by Tracy Caulkins, who won five times at the 1978 worlds, and Libby Trickett, who did it in 2007.

Franklin also joins Michael Phelps, Mark Spitz, Australia’s Ian Thorpe and East Germany’s Kristin Otto as the only swimmers to capture as many as six golds at either worlds or an Olympics.

Quite a club.

“I still can’t really believe that it happened,” Franklin said.

The Aussies took the silver in 3:55.22. Russia held on for the bronze (3:56.47).

Franklin completed a grueling week in which she competed in eight events. She dropped out of the 50 backstroke after swimming in the preliminaries of the non-OIympic event, wanting to focus on more important races, and took fourth in the 100 freestyle.

Otherwise, it was all gold.

“I knew I had to get out there for my team,” Franklin said. “We had really tough competition in that race, so we were sitting there in the ready room and we said, ‘No matter what happens, we’re just going to do our best and have fun and we can’t let each other down if we do that.’ So I just went out there and it hurt really, really bad, but now we’re done and we’re all super excited.”

The victory in the final race of the meet came after a stunning result for the Americans in the next-to-last event.

The men appeared to have an easy victory in their 400 medley relay, but 19-year-old breaststroker Kevin Cordes, the least experienced member of the foursome, left too soon on the exchange between the first and second legs.

The U.S. team, which touched nearly one and a half seconds ahead of France, was disqualified. The French moved up to take the gold, while the silver went to Australia and Japan snatched the bronze.

“A relay disqualification is not a particular individual’s fault,” said Nathan Adrian, who swam the freestyle anchor in vain. “It’s Team USA’s fault and it falls on all of our shoulders.”

Cordes came into the meet touted as the next great American breaststroker, but he endured a tough week in Barcelona. The teenager failed to win an individual medal, then cost him and his team a gold in the finale.

“If us four ever step up again, we’re never going to have a disqualification, that’s for sure,” Adrian vowed. “It will really motivate him. I don’t doubt if in the next couple years we’re going to have the fastest breaststroker in the world swimming for Team USA. This could be a catalyst for that.”

Cordes stood on the deck in disbelief, hands on his head, but the replay showed he clearly left the block before backstroker Matt Grevers touched the pad. Ryan Lochte could only shake his head, having contributed a strong butterfly leg that didn’t matter. He was denied his fourth gold medal of the meet, leaving him tied with Chinese star Sun Yang as the winningest male swimmers.

Franklin stood above them all — even though, amazingly enough, she was not even chosen the top female swimmer of the meet.

That award went to fellow American Katie Ledecky, who won four golds and set two world records. She edged out Franklin based on a formula that doesn’t count the relays and gives bonus points for world marks.

Sun was named the top male swimmer after sweeping the freestyle distance events. He closed with a victory in the 1,500 free, adding to his triumphs in the 400 and 800. After dueling with Canada’s Ryan Cochrane most of the way, the Chinese star turned it on the last two laps and won going away in 14:41.15.

Cochrane took the silver in 14:42.48, while Italy’s Gregorio Paltrinieri earned bronze with a time of 14:45.37. Americans Connor Jaeger and Michael McBroom finished off the podium in fourth and fifth.

“My training has not been so systematic, so it was a pretty tough race,” Sun said through a translator. “I really appreciated my opponent pushed, otherwise I wouldn’t have been able to make it. After all my races I felt a bit fatigued. But I just tried to convince myself to stay with him because I knew that in the last 100 I had the advantage.”

Yang’s week also included the fastest leg by far on the 800 free relay, which almost singlehandedly give China a bronze medal in that event.

In other events on the final night at the Palau Sant Jordi, Japan’s Daiya Seto held off American Chase Kalisz to end U.S. domination of the 400 individual medley, Hungary’s Katinka Hosszu won the 400 individual medley, and Ranomi Kromowidjojo of the Netherlands took the women’s 50 freestyle.

Seto touched in 4:08.69 to take gold in a race that had been won by U.S. stars Lochte and Michael Phelps at every major meet since the 2005 worlds in Montreal.

Phelps is retired — for now — and Lochte has dropped the grueling race, at least for this season.

The 19-year-old Kalisz, who trains at Phelps’ club in Baltimore, was far back after the butterfly and backstroke legs. But he began to close on the breaststroke and nearly caught Seto on a freestyle dash to the finish. He settled for silver in 4:09.22, while the bronze went to Brazil’s Thiago Pereira in 4:09.48.

“I’m very excited about that,” Kalisz said. “The front half isn’t really my strong part, so it’s just staying right there and keeping myself mentally in check, knowing that these guys are better backstroke and butterflyers than me. Breaststroke is my strong point. So it’s just staying in there until that and coming home as hard as I can on freestyle.”

American Tyler Clary was fourth after taking the silver behind Lochte at the 2011 worlds.

Hosszu was more than 2 seconds under world-record pace through the first three legs, giving her a big enough lead to hold on in the freestyle. She touched in 4:30.41, while Spain’s Mireia Belmonte thrilled the home crowd by taking silver in 4:31.21. Elizabeth Beisel of the United States earned the bronze in 4:31.69, about a second ahead of hard-charging teammate Madeline Dirado.

Kromowidjojo’s victory was a reversal of the 100 free, which was won by Australia’s Cate Campbell with the Dutch sprinter taking the bronze. Campbell took silver this time, just 0.09 behind the winner’s time of 24.05. Britain’s Francesca Halsall grabbed the bronze in 24.30, her country’s only medal of a hugely disappointing meet.

Simone Manuel of the U.S. was seventh.

There were a pair of finals in non-Olympic events, as well.

Yuliya Efimova won the 50 breaststroke, getting back at the swimmer who took her world record in the semifinals. The Russian claimed gold in 29.52, while record holder Ruta Meilutyte settled for the silver in 29.59. Hardy took the bronze in 29.80.

Camille Lacourt of France won the first race of the session, the men’s 50 backstroke, with a time of 24.42. Grevers tied for the silver with another Frenchman, Jeremy Stravius, at 24.54.