David Rudisha has been ruled out of the forthcoming World Championships in London through injury.
The 800 metres world record holder will miss out on a return to the stadium where he set his ground-breaking mark of one minute 40.91 seconds in winning Olympic gold five years ago.
It was hailed at the time by London 2012 chairman Lord Coe as the standout performance of the Games.
The Kenyan said on Twitter: “Its sad and disappointing to announce my no show in the forthcoming #london2017 WC due to a quad muscle strain.”
Rudisha retained his Olympic title in Rio last summer and would also have been the defending world champion in London, having won his second world title in Beijing two years ago.
The 28-year-old is ranked only 19th in the world this year, but his absence still deprives the London championships of one of the sport’s biggest stars.
Fellow Kenyan Emmanuel Korir and Botswana’s Nijel Amos are expected to battle for the gold in Rudisha’s absence.
The World Championships get under way at the London Stadium on Friday.