KAZAN - Britain's James Guy held off a host of Olympic champions to win his first world title, the men's 200m freestyle, at the world championships on Tuesday. After claiming silver in the 400m freestyle behind China's Sun Yang, Guy came from third at the final turn to touch the wall in one minute 45.14 seconds. He beat Sun and Paul Biedermann of Germany into silver and bronze respectively. Ryan Lochte, of United States, was fourth.

The stirring finish from the 19-year-old dented Sun's bid for four world titles. "It was quite a nice feeling, as I never thought I'd race Ryan, one of my heroes, and racing head-to-head against him, touching the wall and becoming world champion is amazing," said Guy. "I tried to focus on myself (in the final 50m) and I knew the boys would go out hard. I also knew I had a good back end because of the 400m, so I tried to play to my strengths."

As expected, Katie Ledecky, of the United States, won her second world title in three days, coasting to victory in the women's 1500m freestyle and lowering her world record in the process. The 18-year-old high school graduate raced away from the field in the opening salvos, recording 15:25.48 to lower the mark she set on Monday by 2.23 seconds. Thirty minutes later, Ledecky was back on the starting blocks for her women's 200m freestyle semi-final, summoning all her strength to qualify sixth-fastest.

"I was prepared for it and it did hurt a lot, but I got the job done and it feels really good," said Ledecky. She had avoided the same schedule at the 2013 championships, but opted to include a fourth event in Kazan in the build-up to the Rio Games, given that the 1500m is not on the Olympic programme. "I have 2,000 more metres of racing here and I'm not thinking about 2016 just yet," she added.

The American, chasing four individual world titles, will face a tough final after Italy's Federica Pellegrini and Missy Franklin, of the United States, took the first two final berths. Australia took two golds in less than an hour after securing both men's and women's 100m backstroke titles. Emily Seebohm led home a brilliant one-two in the women's event, claiming gold with the year's world leading time of 58.26 seconds, ahead of compatriot Madison Wilson in 58.75 seconds. Mitch Larkin then held off 2011 world champion Camille Lacourt, of France, in the men's 100m backstroke on the final stroke. The 22-year-old touched in 52.40 seconds, just 0.08 seconds ahead of Lacourt.

The defending champion, Australia's Matt Grevers, took bronze.

In the final event of a pulsating session, favourite Yuliya Efimova delighted the home crowd by taking gold in the women's 100m breaststroke. The Russian, competing in her first major competition since her doping ban ended in February, posted 1:05.66, with Lithuanian rival Ruta Meilutyte claiming silver.

Guy's compatriot, Adam Peaty, earlier set a world record for the men's 50 metres breaststroke as he continued his Kazan rivalry with South Africa's Cameron van der Burgh. Peaty's time of 26.42 seconds broke the previous record by 0.20 seconds, set by Van der Burgh, the defending champion, earlier in the day.

The Briton will be favourite to land his second title of the week after winning 100m breaststroke gold on Monday. Meanwhile, Conor Jaeger, of the United States, qualified fastest for Wednesday's men's 800m final, with seven minutes 44.77 seconds. Defending champion Sun recorded the sixth-fastest time, 3.10 seconds down on the American.