Australia's James Magnussen claimed revenge on Olympic champion Nathan Adrian while Missy Franklin struck gold for the fourth time at the swimming world championships in Barcelona on Thursday.

Magnussen retained his 100m world freestyle title with American duo James Feigen and Adrian taking silver and bronze respectively.

The heavily-fancied Magnussen missed out on gold in London last year by just one hundredth of a second and his preparation was later questioned after he admitted to taking sleeping pills during the Games to help him relax.

"I've put a lot behind me in the past 6-12 months and this is probably one of my proudest moments given what I and my support team have overcome to get me here," he said.

And the man known as 'The Missile' said the extra support of his teammates, in stark contrast to what he experienced in London, was an extra help.

"The Australian swim team, both swimmers and staff, really helped me through the past few days.

"Last year I struggled and I struggled alone with my coach. We felt a bit isolated whereas this year everyone was right behind us. I was representing a team I was proud to represent."

It was a good night all round for Australia as Cate Campbell secured her place in the final of Friday's much anticipated 100m women's freestyle.

Australia also took silver in the 4x200m women's freestyle behind a star-studded USA side.

The American line-up included Katie Ledecky and Franklin who collected their third and fourth golds of the championships so far and Franklin insisted that despite her frantic seven-event schedule she does have time to enjoy the moment every time she stands atop the podium to sing the national anthem.

"Being up there and singing your anthem completely out of key at the top of your lungs is when you know the hard work has paid off," she joked after another successful evening that also saw her comfortably advance into the 100m freestyle final.

There was more American success as Ryan Lochte claimed his first gold of the meet and a 13th world championship gold of his career in the 200m individual medley as he led home 18-year-old Japanese sensation Kosuke Hagino and Brazil's Thiago Pereira.

Victory meant Lochte has now matched Michael Phelps' record of winning three consecutive world championship titles in the event, but he insists he doesn't feel the pressure of having to fill the retired Phelps' shoes.

"I don't know if I could ever replace Michael. What he's done for the sport is unheard of, he is one of the greatest swimmers ever.

"I'm just trying to do my part and help team USA as much as possible."

Lochte also set up another showdown with Hagino on Friday as both men qualified for the 200m backstroke final.

China secured two gold medals in the women's 200m butterfly and 50m backstroke through Liu Zige and Zhao Jing respectively.

Zhao was followed home by 17-year-old compatriot Fu Yuanhui, whilst Japan's elder stateswoman Aya Terakawa picked up her second bronze of the championship.

Spain's Mireia Belmonte Garcia and Hungary's Katinka Hosszu also claimed their second medals in the 200m butterfly, but were powerless to stop Liu retaining the title she won on home soil in Shanghai two years ago.

The performance of the night though came from Dane Rikke Moller Pedersen in the women's 200m breaststroke semi-finals as she set a new world record time of two minutes 19.11 seconds.

"I am incredibly happy, excited and looking forward to the final now," said a delighted Pedersen.

In the men's 200m breaststroke semi-finals Olympic champion Daniel Gyurta posted the fastest time with the British duo of Andrew Willis and Olympic silver medallist Michael Jamieson also making the final.