American Rai Benjamin added the 400 metres hurdles world title to his Olympic gold from last year on Friday while Dutch star Femke Bol clinched back-to-back gold in the women's race.
Benjamin was ahead coming out of the final bend and although he clipped the final hurdle cruised home in a world lead 46.52 seconds.
The 2022 champion Alison dos Santos of Brazil took silver in 46.84. Qatar's Abderrahman Samba got bronze as in 2019.
Norway's Karsten Warholm, who had won Olympic gold in world record time in the Tokyo stadium four years ago, failed to get a fourth world title as he hit a hurdle hard on the back straight as he faded dramatically on the home stretch to finish fifth.
Bol was the women's favourite in the absence of Olympic champion and world record holder Sydney McLaughlin-Levrone, who chose the 400m flat instead which she won in the second best time of all time on Thursday.
Bol was unstoppable on the home straight as she won in a world lead 51.54.
American Jasmine Jones took silver in 52.08 and Emma Zapletalova of Slovakia earned a surprise bronze in 53.00 as Olympic silver medallist Anna Cockrell had to settle for fourth and the fellow-American 2019 champion Delilah Mohammad had to settle for seventh in her last big career race.
Friday other finals are the men's and women's 200m and the men's triple jump.
Semi-final rounds
In preliminary action, Jakob Ingebrigtsen and Cole Hocker shook off their 1,500 metres disappointment when they qualified for the 5,000m final.
American Olympic 1,500m champion Hocker came third in his heat while Norway's Ingebrigtsen, the twice defending world and 2024 Olympic champion in the 5,000m, squeezed through in eighth place from the second heat.
Ingebrigtsen had gone out in eighth place in his 1,500m heat as he seemed not fully fit this season, while Hocker was disqualified in the semi-finals.
But European record holder Andreas Almgren of Sweden went out, and strong Dutchman Niels Laros retired after seemingly being spiked.
Kenyan title holder Mary Moraa and British Olympic champion Keely Hodgkinson qualified for the women's 800m final.