The Kenyan broke the world mark at the Berlin Marathon last year.
The two runners are expected to make a charge at winning this weekend's race in the Czech capital.
The Ethiopians would love to repeat their 1-2 finish from 2011.
A slew of sub-2:30 women have come from far and wide to race in New York on Sunday.
The Portugese all-comer's record in the men's and women's marathons could go down this weekend.
The 35-year-old suffered a broken toe during a training run over the summer.
The American running legend will run Sunday's half-marathon in southern California.
Nasty blister forces reigning champion to withdraw.
Past champions and multiple Olympic medalists are listed amongst the top entrants.
Injuries force two top female contenders to the sidelines.