KAZAN, Russia (Reuters) - American swimming great Ryan Lochte became only the second man to win titles in the same individual event in four consecutive world championships when he triumphed in the 200 metres individual medley on Thursday.
The five-time Olympic champion emulated the feat of Australian Grant Hackett, who won four 1,500 metres titles in a row between 1998 and 2005.
Victory for Lochte was secured in the final length as a powerful surge off the wall, using a new rotational technique he has introduced only over the last three weeks, saw him overtake long-time leader Thiago Pereira.
Lochte, who first landed the 200m IM title in Rome in 2009 and has now won at least one gold at the last six editions of the championships stretching back to Montreal 10 years ago, won in one minute 55.81 seconds.
The Brazilian Pereira claimed silver in 1:56.65 while Shun Wang, of China, took bronze.
"It's an honour to go down in history with one of the greatest swimmers in history, Grant Hackett, and it is something I will remember for the rest of my life," said Lochte.
"I'm definitely really humbled and to say you have made history in any sport is one of the coolest things."
Following a poor US trials, Lochte has competed in fewer events at these championships than at any time in the last 11 years.
Yet after finishing outside the medals in the 200m freestyle, his medley gold -- the 16th world title of his glittering career -- demonstrated why the 31-year-old is still a major force in the pool.
It also brought relief to the US team, which had been forced to defend their poor medal return at the championships.
"I'm definitely really humbled to get that win and hopefully I got the ball rolling for Team USA," added Lochte.
Sure enough, the US then won their second title of the evening when 18-year-old Katie Ledecky won her fourth gold of the week in the 4 x 200m freestyle, adding to her three individual victories.
Ledecky and Sweden's Ida Marko-Varga went into the anchor leg neck and neck before the American predictably forged to victory in 7 minutes 45.37 seconds.
With three days of racing left, the two golds propelled the United States past Australia and Great Britain to the top of the medal table, with five golds and 11 medals in total.
China's Ning Zetao surged to the blue riband men's 100m freestyle title, denting pre-race favourite Cameron McEvoy's bid to succeed compatriot James Magnussen, the two-time Australian champion who was forced to pull out of the championships with a shoulder injury.
Ning led from the outset, touching in 47.84 seconds, with McEvoy taking silver, 0.11sec behind, and Argentina's Federico Grabich securing bronze.
"I've had dreams of winning gold medals but I can't believe I've actually done it," said Ning, who was banned for 12 months in 2011 after testing positive for clenbuterol.
China's golden evening continued in the women's 50m backstroke when Yuanhui Fu took gold in 27.11 seconds. Etiene Medeiros of Brazil touched second in 27.26 while Xiang Liu claimed bronze.
Natsumi Hoshi, of Japan, won her first global title in the 200m butterfly, clocking 2 minutes 05.56 seconds, ahead of American Cammile Adam and China's Zhang Yufei.
Sweden's Sarah Sjostrom qualified fastest for Friday's 100m freestyle final, while American star Missy Franklin secured an outside lane in the final by 0.01 seconds.
Editing by Ian Chadband