Canadian sprinter Andre de Grasse is out of the World Championships after tearing a hamstring.
The 22-year-old was considered one of Usain Bolt's main challengers for the 100 metres title on the Jamaican's track swansong in London, which kicks off tomorrow.
De Grasse won 200m silver, 100m bronze and 4x100m relay bronze at last year's Olympic Games and ran a wind-assisted 9.69 seconds in Stockholm in June.
"Earlier this week in practice, I suffered a hamstring tear that has forced me to withdraw from the World Championships," De Grasse said on his Facebook page.
"Injuries are a part of the sport, and the timing of this one is especially unfortunate.
"While I'm in the best shape of my life and extremely disappointed that I will not have the chance to compete for my country in London, I can't forget or be ungrateful for the successes that I've been blessed with up to this point in my career.
"I'll be back stronger and faster than ever."
De Grasse's manager Paul Doyle said that MRI scans suggested that the sprinter would be out of action from around four to six weeks.
His injury prevents a spicy clash with Bolt after De Grasse's coach Stuart McMillan had claimed the Jamaican denied his rival entry into the 100m field at a Diamond League meeting in Monaco - a charge the eight-time Olympic gold medallist denied.
Asked at a London press conference on Tuesday who might fill his shoes after he retires, Bolt replied: "I'm not going down that road.
"The last guy I said was going to be great disrespected me."
The comment was seen as a reference to De Grasse, who pushed Bolt to the line in the Olympic 200m semi-finals, eliciting a finger-wag from the greatest sprinter in history.