Kenya's David Rudisha's hopes of adding world 800 metres gold to the Olympic title he won in a world record time at the same track in the 2012 London Olympics have been dashed because of injury.
The 28-year-old — who ran an astonishing time of 1min 40.91sec to take gold in 2012 — took to Twitter to reveal he could not take his place in the London Stadium for the championships.
"It's sad and disappointing to announce my no show in the forthcoming #london2017 WC due to a quad muscle strain," tweeted Rudisha, who was the defending champion.
The absence of the two-time Olympic champion — whose run in 2012 was acclaimed as the standout performance of the Games by London 2012 chairman and athletics great Sebastian Coe — could pave the way for compatriot Emmanuel Korir or the man who chased him home in London in 2012, Nijel Amos of Botswana.
The championships get underway on Friday.