Living up admirably to his role as pre-meet favourite, Marcus Krah of the US produced a confident run to capture the 110m hurdles title, clocking 13.25.
Visibly ahead by the second hurdle, the 18-year-old gradually added to his lead over the next five barriers and maintained the advantage to convincingly fend off the late-race challenge by teammate Amere Lattin who took silver in 13.30, a personal best by 0.02 seconds.
Krah equalled his career best to lead the first US 1-2 finish in the event and the first by any nation since Colin Jackson and Jon Ridgeon at the championships' inaugural edition in 1986.
"It feels amazing, unbelievable," said Krah, the US junior champion who lost just one outdoor contest this season.
"Setting a PB was a goal, but most of all it was about winning gold. I never thought I would actually get it until I got here."
Lattin in turn barely edged Japan's Takuma Furuya who clocked 13.31, an Asian U20 record.
"I executed the race the way my coach wanted and I set a PB in the final, so I have to be happy about that," said Lattin, 19, who was a notable fifth at the NCAA Championships last month.
Just behind, De'Jour Russell of Jamaica was fourth in 13.39, the day after clocking 13.20 in the semifinals, a world U20 lead.
Dawid Zebrowski of Poland, who entered the championships with a 13.64 PB, was fifth in 13.45, his second career best in as many days.
Bob Ramsak for the IAAF