Asafa Powell, the fastest man in the world this season over 100m and defending champion Usain Bolt's biggest rival, will miss the event at the World Championships, his agent confirmed on Thursday.
The 28-year-old Jamaican has failed to recover from a niggling groin injury that also saw him skip the London Diamond League meet earlier this month, Paul Doyle told AFP.
"He's out of the 100m but he hopes to be back for the 4x100m relay," which will be raced on the final day of competition on September 4, Doyle said.
The men's 100m kicks off on the opening day of the Daegu worlds, with the final being run on Sunday night.
"He's still suffering groin pains from the Budapest meet (in July). He pulled out of the London meet (August 5-6) and has not recovered suffienctly to take part in the 100m," Doyle said.
"He now has nine days to get ready for the relay."
Powell's withdrawal from the 100m comes as devastating news for sports fans who have revelled in the move back to prime form from the affable Jamaican who held the world record between June 2005-May 2008.
It also accompanies the pull-outs of American Tyson Gay (injury) and Jamaican Steve Mullings (doping), effectively depriving Bolt of running against his three biggest rivals on the world stage.
Powell clocked a world season lead of 9.78 seconds at the Lausanne Diamond League in early July, dipping under the 9.8sec mark for the eighth time in his career.
Only Bolt (five times with a world record best of 9.58sec) and Gay (five times with a best of 9.69sec) have run faster, while another Jamaican, Nesta Carter, has also managed to time 9.78sec once in his career.
"We expected him to run here in Daegu but it was too short," Doyle said. "Wee took the decision today. He is upset but he knows there is nothing he can do.
"He's got to now concentrate for next year and the Olympics. It's just bad luck, nothing else. At those speeds, you ask a lot of your body."
Powell was earlier a no-show at a Jamaican team press conference and teammate Michael Frater let slip that something was awry.
"I didn't come expecting to run the 100m but unfortunately Asafa couldn't make it," revealed Frater, who initially failed to book an individual berth for the 100m but was included in Jamaica's 4x100m relay team.
Frater's teammates Yohann Blake and Nesta Carter, who will both race the 100m, then remained mum after persistent questioning over the former's gaffe.
"I don't think anything's been decided," Frater eventually added.
Jamaican team official Grace Jackson said that no decisions had yet been taken pending a "technical meeting", and Bolt also said that any withdrawal was news for him.
"Asafa's out?" he asked. "This is the first time I'm hearing about it so I can't answer that question."