James Guy is already eyeing an upgrade at the Olympics after claiming 400m freestyle silver at swimming's World Championships in Kazan. Guy lead the race through 300m but faded down the final two lengths as China's Yang Sun came through snatch gold by over a second. But Guy's time of 3:43.75 was still a new personal best and British record and nearly a second quicker than Canadian bronze medallist Ryan Cochrane. He's the first British world medallist in the event since Paul Palmer claimed bronze in 1998. “Everyone wants to win obviously but I can’t be happier to win a medal at the World Championships – I’m over the moon with that one,” Guy told British Swimming. “I tried to race that from the start and back-end it. Sun Yang is a distance swimmer so he has more endurance than I do so my best chance was to go out hard and try and hold on. “It was stroke for stroke and that’s what it will be like next year as well, maybe with a couple more guys in there so that will be the big one. “I know there’s more there as well – I died a little bit on the back 50m so that’s something to work on for next year.” Jazz Carlin admitted frustration after again finishing fourth in the women's 400m freestyle, her time just four tenths of a second behind Australian bronze medallist Jessica Ashwood. American Katie Ledecky took gold in a championship record to underline her Rio credentials and give Carlin a reminder of the challenge ahead. “I gave it my best shot,” said Carlin, who also finished fourth in the 400m freestyle at the 2013 World Championships. “When you get to a World Championship, you’re really racing the best in the world. That was my best and to come fourth is really disappointing." Adam Peaty set up a fascinating showdown with South Africa's Cameron Van Der Burgh as he qualified fastest to Monday's 100m breaststroke final. Peaty leads the world rankings this season and probably would have lowered his own world record had it not been for a sluggish first 30 metres in his semi-final. But he still recorded a championship record 58.18 seconds while he'll be joined in the final by British team-mate Ross Murdoch. “I’m not feeling any pressure – there’s nothing," said Peaty. “It doesn’t quite feel like a World Championships and I think that’s a good thing because I’m able to stay so chilled. It's going to be a really good final." Elsewhere, Ben Proud was sixth fastest into the 50m butterfly final while Siobhan Marie O'Connor progressed as second fastest to the 200m medley final, where former world medallist Hannah Miley will also line up. However, Rachael Kelly was 12th quickest in the 100m butterfly, just 0.22 secs of a qualifying place. © Sportsbeat 2015