The rivals have been competing against each other since 2006.
Kenyan Gladys Cherono takes the women's race.
Zersenay Tadese will fight the temperatures as much as his competitors.
World record holder could better his mark next week.
He needs to run faster than 58:23.
The Eritrean crushed the field on a warm day in Bulgaria.
Eliud Kipchoge will be giving the Eritrean a run for the money.
Sweltering conditions made the race a tactical affair.
The 24-year-old Kenyan road-running ace is ill.