Ethiopia's men's world champion Tamirat Tola said on Friday he had pulled out of October's London Marathon due to muscle fatigue.
Tola won gold in Eugene, Oregon, last month in a championship record time of two hours, five minutes and 36 seconds.
"It is with great regret that I am unable to run this year’s TCS London Marathon," said the 31-year-old.
"Unfortunately, since the World Championships I have had problems with muscle fatigue and have not yet been able to resume training."
London Marathon organisers said world silver and bronze medallists Mosinet Geremew of Ethiopia and Somalia-born Belgian Bashir Abdi would be on the start line on October 2 along with Ethiopia's defending champion Sisay Lemma.
Ethiopia's Kenenisa Bekele, the second fastest marathon runner of all time, will also compete.
Last year's women's runner-up Degitu Azimeraw of Ethiopia has also withdrawn. Kenya's world record holder Brigid Kosgei, a two times winner, and reigning champion Joyciline Jepkosgei lead the entry list.