|World Aquatics Championships on the BBC|
|Hosts: Budapest, Hungary Dates: 23-30 July|
|Coverage: Live across BBC Two, BBC Red Button, Connected TV, online, BBC Sport mobile app and BBC Radio. Click for full times.|
Britain's Adam Peaty broke the 50m breaststroke world record for the second time in a day as he reached the World Aquatics Championships final.
The defending champion, 22, won the semi-final in 25.95 seconds, becoming the first person to break 26 seconds and eclipsing his 26.10 in the heats.
"I honestly can't believe it. I can't even think. I just went out there and did what I do," he told BBC Sport.
Peaty retained his 100m breaststroke title in Budapest, Hungary on Monday.
He added: "The hard work has gone on in the gym. I am looking for areas of where I can improve and hopefully get down to mid-25."
A magical day for Peaty
After winning 100m gold, Olympic champion Peaty predicted "something special" on Tuesday.
He returned to the pool to break the 50m world record of 26.42 he set at the 2015 World Championships in Russia.
A dominant Peaty went almost half a second quicker in the semi-final, finishing 0.73secs clear of Felipe Lima of Brazil (26.68). South Africa's Cameron van der Burgh - 50m breaststroke world champion in 2013 - was third in 26.74.
"I thought I was going to go slower in the semi-final because I was a little bit less energetic," Peaty said.
"I was on such a massive high from this morning and it was so hard to ignore the fact that I did a world record and try to get myself emotionally ready."
If Peaty wins Wednesday's final - scheduled for 17:17 BST - he will replicate his achievements at the World Championships two years ago when he took the 50m and 100m titles.
The multiple record-breaker
- Peaty has now broken the 50m breaststroke world record four times - the first in Berlin in 2014
- He holds the top 10 times in the world for the 100m breaststroke
- He swam his 100m world record of 57.13 at the Rio Olympics in 2016
- He is attempting to become the first swimmer to break the 57-second mark in the 100m breaststroke, a challenge he refers to as 'Project 56'
- He was also part of the British 4x100m mixed medley relay team which broke the world record for a second time at the 2015 World Championships
'This kid is unbelievable' - analysis
OIympic bronze medallist Steve Parry
He can't believe it and I can't believe it. In my life I have never seen swimming like that.
This kid is absolutely unbelievable. Does he know any boundaries whatsoever? I don't think he does.
He's almost taken a second off everyone else over a 50m dash. It's not about gold medals for him any more - it's about how much he can move the sport on.
Double Olympic champion Rebecca Adlington
He shocked himself. It is the first time in a long time that I have seen him genuinely shocked.
His start was better than this morning but he still has room to improve that, which is insane.
Which other Britons were in action?
James Guy failed to defend his men's 200m freestyle title as China's Sun Yang won gold.
Guy finished fifth while compatriot Duncan Scott was fourth, 0.04secs behind Russia's Aleksandr Krasnykh in third. Townley Haas of the United States won silver.
Kathleen Dawson was eighth in the women's 100m backstroke final in 59.90. Canada's Kylie Masse took gold in a world record 58.10.
Sarah Vasey also finished eighth in the 100m breaststroke as Olympic champion Lilly King of the United States won in one minutes 4.13 seconds - a new world record.