Kazan - Reigning champion Cameron van der Burgh of South Africa expects the world 50m breaststroke record he broke on Tuesday to fall again at Kazan's world swimming championships.
Van der Burgh, who is defending his 50m title, clocked an official time of 26.62 in Tuesday's heats to shave 0.05 off the record he set at the 2009 championships in the era when the performance-enhancing neoprene suits were still permitted.
Britain's Adam Peaty, who beat Van der Burgh on the wall in Monday's 100m breaststroke final here, had swum 26.62 at the European championships in Berlin last August, but his time has still not been ratified by swimming's governing body FINA.
The South African predicts the record will be lowered again when the pair battle over the sprint distance in Tuesday night's semi and Wednesday's final as Peaty was just 0.06 slower in his heat.
"I knew we were going to break it, that (Peaty's record) time should have been accepted a while ago," said Van der Burgh, as Slovenia's Damir Dugonjic (26.70) also posted a fast time going into the semis.
"I would have already liked to have broken it two years ago (at the 2013 Barcelona world championships), but I got sick before the final.
"This record is not going to stand anyway. If I don't get it, it'll go to Damir or Adam, so I think we can get ready for a new time."
This is the fifth time a world record has been broken in Kazan.
Sweden's Sarah Sjostrom twice broke the women's 100m butterfly record, Hungary's Katinka Hosszu broke the women's 200m individual medley mark and Katie Ledecky of the USA bettered her own 1 500m freestyle.
It is the first men's record to fall at a world championships since 2011.
"It's nice to be joining the ladies," grinned Van der Burgh.
"It's always an honour to get a world record, but you can't get too excited.
"It's going to fall again between any of the three of us and it's going to be a dogfight for sure in the final on Wednesday night."
Van der Burgh says Peaty has helped push for faster times since the 20-year-old Briton announced his arrival by winning the 2014 Commonwealth Games 100m title.
"It's good for the sport to push things faster," said Van der Burgh.
"The stroke has evolved a lot, we are swimming much higher in the water and almost emulating what the (neoprene) suits used to do.
"The suits helped you float on top of the water and Adam coming in with a high stroke rate has also helped. You always keep learning from that."
After taking time off earlier this year to recover from a troublesome shoulder injury, Van der Burgh, the Olympic 100m champion, says he is just glad to be at his best a year from the Rio de Janeiro games.
"It's nice to just train properly again, the last four months have been the first time I have been able to go from one session to the next and it gives me a lot of confidence ahead of Rio knowing I am able to string sessions together," he said.
"It's going to be one hell of a race there."