World class athletes will fight it out for top honours against newcomers who include Collins Tanui and Geoffrey Kosgei in the 42 km full marathon which has a grand prize of $18,000 for both men's and women's categories, reports Xinhua.
This year's total entry is a sharp drop from over 21,000 participants in 2013 and officials were hard placed on the reasons for the drop.
"We will analyse the causes for the reduction in numbers and give a comprehensive report after the race. As of now we cannot tell the exact cause," local organising committee chairman Peter Gitau said.
"However, we promise to deliver an exceptional world class event that will exceed expectations," Gitau said.
The marathon has emerged as catapult point for budding athletes.
World marathon world record holder Dennis Kimetto (2:02.57), the third fastest marathon runner Geoffrey Mutai and Commonwealth Games champion Irene Jerotich have all participated in the race.
Kenyan police have promised maximum security at the event, whose proceeds go towards efforts to eradicate avoidable blindness in children under 15 years of age and in which over 7,000 children in Kenya have had their eyesight restored.