Adam Peaty shakes head in disbelief after clocking astonishing second world record in Budapest

Adam Peaty shook his head in disbelief after clocking an astonishing second world record in the 50 metres breaststroke at the World Championships in Budapest on Tuesday.

Olympic champion Peaty won over 100m on Monday and predicted "something special" over 50m.

He returned on Tuesday morning and improved his own world record by 0.32 seconds to 26.10secs, 0.44 ahead of his nearest rival, Cameron van der Burgh of South Africa.

But he was not finished there. The 22-year-old Uttoxeter swimmer went even quicker in the evening semi-final, clocking 25.95secs.

He was 0.73 clear of his nearest rival - a huge margin over two lengths of the pool, let alone one.

Duncan Scott and James Guy earlier missed out on adding to Britain's medal collection, which included Ben Proud's 50m butterfly gold on Monday.

Scott and Guy had to settle for fourth and fifth place respectively in the 200m freestyle as Olympic champion Sun Yang of China won gold.

Peaty won 50m and 100m world titles in Kazan, Russia two years ago and is on course to do the same here.

Brazil's Felipe Lima, with a time of 26.68, won the first semi-final ahead of Van der Burgh, Peaty's predecessor as world champion in 2013.

The South African clocked 26.74, progressing in third place.

Peaty is also likely to be part of the British team in the 4x100m mixed medley relay on Wednesday night, providing they qualify from the morning heats.

Britain won the now-Olympic event in 2015 and will be confident with Peaty on the breaststroke leg.

While Peaty is enjoying another stellar major championships, Guy's has again been disappointing on an individual level.

The 21-year-old Bury swimmer won 200m gold and 400m silver in 2015, but was fifth and sixth, respectively here. He has the 100m butterfly and relays to come.

Guy was fourth in the 200m at the Olympics, behind Sun, whose image is tainted by an anti-doping infringement earlier in his career.

Sun, the 400m champion on Sunday, added another world title, winning in one minute 44.39 seconds.

Townley Haas of the United States took silver in 1min 45.04secs and Aleksandr Krasnykh of Russia bronze in 1:45.23 - slower than Scott and Guy had swum in the semi-finals on Monday night.

Scott had qualified fastest and Guy, the defending champion, second quickest, but Stirling's Scott finished in 1:45.27, 0.04 off the podium, and Guy in 1:45.36 after paying for a fast start.

"I think I got a little bit carried away at the start of the race," Guy said.

"It would've been nice to go a 1:44. It's very disappointing.

"I know it's there. It's just doing it on the right day. It's a four-year plan.

"My room-mate (Peaty) winning gold and Ben Proud winning gold, I want to be up there too. But everything happens for a reason."

Scott, who begins his 100m freestyle campaign on Wednesday, is optimistic for the 4x200m freestyle relay on Friday and was content with his swim.

Scott said: "I've got to keep my head held high. First individual 200m free final. It's what I came here to do in the 200.

"Finishing fourth and not doing my best time in the final is pretty gutting, but I'm just going to have to move on from that.

"I'm proud of that swim. I don't think I did anything wrong, just others stepped up and performed when they needed to."