American favourite Justin Gatlin added the world 100m title to his Olympic crown with a dominant win in Helsinki.
The 23-year-old quickly recovered from a slow start to accelerate away from the field at the halfway mark and win in a season's best of 9.88 seconds.
Jamaican Michael Frater was awarded the silver after a photo-finish with resurgent defending champion Kim Collins - both clocked 10.05.
Britons Jason Gardener and Marlon Devonish had failed to reach the final.
"It feels great adding another medal to my Olympic title," Gatlin told BBC Sport. "I had to make sure I got myself one.
"When I felt I was in the lead, I didn't coast but I knew I had enough to win it.
"I could have gone even faster and I think I have a lot left in the tank.
"The target is two more golds. I just wanted to get the 100m done and get ready for the 200m and the relay."
When the 23-year-old claimed his first major title in Athens last summer the race went down to the wire, with five men dipping under 10 seconds.
But things were different in the cool Helsinki conditions on his Worlds debut as Gatlin was able to dominate a field missing his chief rival, world record holder Asafa Powell.
Gatlin finishes ahead of Frater (right) and Collins (far left)
The Jamaican pulled out of the event because of a groin injury and had to watch the race from the stands.
"He's a great champion and I respect him a lot," conceded Powell after watching Gatlin's awesome display.
Only Powell has run faster than Gatlin this season and the American's winning time is only the fourth fastest of the year.
The Bronx-born athlete reeled in compatriot Leonard Scott, who had got a good start, before leaving his opponents to fight it out for silver and bronze.
While Scott faded Frater and Collins broke through and crossed the line side-by-side to edge Olympic runner-up Francis Obikwelu out of the medals.
"People say if I'm behind in a race then I stay behind," said 22-year-old Frater.
"But I can't complain because the only person in front of me today was Justin Gatlin."
Collins' chances of repeating his surprise success in Paris two years ago had been written off after he just scraped into the semi-finals.
But the St Kitts and Nevis athlete shrugged off his critics by claiming a deserved bronze.
"This is what the championships are about - coming in and performing," Collins said.
"I came in as a fastest loser but once I'm in the finals, watch out for me because I'll see you on the podium."