By Iain Rogers
BARCELONA (Reuters) - The final day of the world swimming championships belonged to Missy Franklin as the American teenager became the first woman to win six golds at a single edition thanks to the U.S. triumph in the medley relay on Sunday.
In a frenetic session at Barcelona's Palau Sant Jordi, there was high drama when the U.S. men were disqualified from their medley relay after finishing well ahead of France, while China's Sun Yang won a second consecutive gold in the men's 1,500 freestyle to complete a rare treble of distance titles.
Among the men, there were triumphs for Frenchman Camille Lacourt in the 50 backstroke and Japanese teenager Daiya Seto in the 400 individual medley, while Russia's Yuliya Efimova won gold in the women's 50 breaststroke to add to her title over 200 meters.
Ranomi Kromowidjojo of the Netherlands claimed the 50 freestyle gold and Katinka Hosszu of Hungary followed up her victory over 200 meters to win the 400 medley.
After a flurry of finals, the women's medley relay was the final event on the eighth day of racing in the hilltop pool and Franklin and her team mates did not disappoint.
The 18-year-old swam a blistering opening backstroke leg to give the Americans a healthy lead they never relinquished and their success followed her titles in 100 and 200 backstroke, 200 freestyle and the 4x100 and 4x200 freestyle relays. She was fourth in Friday's 100 freestyle.
"I think the whole week was kind of difficult swimming this many events but I think I've proven a lot to myself and being able to swim as much as I swam," the perpetually chirpy Colorado native told a news conference.
"Moving forward I'm excited for more opportunities to swim like this again."
Franklin's sixth gold in Barcelona is one more than the previous record of five she jointly held with compatriot Tracy Caulkins and Australia's Libby Trickett.
The only other woman to win six golds at a single major meet is East German Kristin Otto at the 1988 Seoul Olympics.
After her three world titles at the 2011 championships in Shanghai, Franklin is also tied for the most golds overall with Trickett on nine. She also owns four Olympic titles.
The biggest shock of the night came immediately before Franklin took to the pool when a misjudgment by her male compatriots handed France relay victory.
The Americans touched well ahead before the stadium announcer drew gasps from the crowd and prompted wild celebrations among the French when he announced the winners had been disqualified "for an early exchange".
Official results showed 19-year-old Kevin Cordes, swimming the second, breaststroke leg, had gone 0.04 seconds too early.
"A relay disqualification is not a particular individual's fault," U.S. team member Nathan Adrian told reporters.
"It's Team USA's fault and it falls on all of our shoulders," he added.
"It will really motivate him. In the next couple of years we're going to have the fastest breaststroker in the world."
The Americans were denied what would have been a 12th triumph in the event in 15 championships since the inaugural edition in Belgrade in 1973 and Ryan Lochte missed out on a fourth gold of the week.
The drama echoed an incident at the world championships in Melbourne in 2007.
Michael Phelps' bid to win eight golds was ruined when the U.S. team was disqualified from the heats of the medley relay.
Phelps had already won a record-equaling six titles and was expected to win his final two events on the last day of competition to make it eight from eight.
He safely qualified for the 400 individual medley but lost his chance to compete in an eighth final when Ian Crocker left the starting blocks one-hundredth of a second too early.
Many had expected Chinese Sun to challenge the world record he set to win Olympic 1,500 freestyle in London last year.
In a relatively slow race he stayed on the shoulder of Canada's Ryan Cochrane before pulling inexorably away in the final 100 meters.
The Olympic champion and world record holder matched American teenager Katie Ledecky in winning 400, 800 and 1,500 freestyle titles in the Catalan capital.
The towering 22-year-old is only the second man to achieve the feat at a world championships after Australian Grant Hackett at the 2005 edition in Montreal.
The French men's relay triumph capped a fine day for the European nation, who pipped the U.S. to win last Sunday's 4x100 freestyle event.
Lacourt's team mate Jeremy Stravius tied for silver in the 50 backstroke with American Matt Grevers, only the second time two swimmers have finished equal second at a world championships after it happened the 100 backstroke in 2003.
Athletes thoughts now turn to the next edition in Kazan, Russia in 2015 before they gear up for the Olympic Games in Rio de Janeiro a year later.
(Additional reporting by Emma Pinedo in Madrid, Gregory Blachier in Paris and Josh Reich in London, editing by Pritha Sarkar)