World 800m Champion David Rudisha will not recover in time to defend his title at the Moscow edition next month.
The Olympic champion wrote to Athletics Kenya on Monday ending any doubts about his chances of defending his title, reports Xinhua.
"I regret that I will not be able to defend my 800m title at the World Championships next month," said Rudisha.
"My knee problem is progressing well but unfortunately not fast enough to enable me recover in time for the Championships. I therefore take this opportunity to wish my colleagues success at the event."
David Okeyo, Athletics Kenya (AK) vice president, confirmed that Rudisha had withdrawn from the Worlds, which means Kenya will have to depend on Anthony Chemut, Ferguson Rotich and Timothy Kitum, the Olympic 800m bronze medallist.
As the defending champion, Rudisha had automatic qualification on wild card, which would have gifted Kenya with four entries, unlike other countries that will only enter a maximum of three athletes in a discipline.
Rudisha injured his knee in June while training in New York. His coach Colm O'Connell had said a week ago that they were monitoring his progress hoping he will recover for the Moscow event starting August 10.
It therefore came as no surprise when Rudisha failed to turn up in Nairobi last weekend for the country trials, where a team of 49 athletes was selected.
Other two medal prospects that Kenya will miss are double world champion in 10,000 and 5,000m Vivian Cheruiyot, Olympic 10,000m silver medallist Sally Kipyego, and world marathon Champion Abel Kirui.
"Kenya is not a one man team. We have athletes that can replace us," said Cheruiyot.
"I am out expecting my first baby. But I have faith the team will do well in Moscow. We have faith that the athletes selected have what it takes to beat anyone any day."
Rudisha was injured in June while running New York's Central Park, which forced him to pull out of the Diamond league Meeting in Eugene, Oregon. He has not raced since.
These rule out a possible repeat of London performance where Rudisha raced to a new World Record of 1:40.91. He has also run a world leading time at the Doha Diamond league meeting in May.
