Kenyan is a dark horse to win Monday's race.
30-year-old American is in the midst of a comeback, and he hopes his hard work pays off in Boston.
The fastest American marathoner of all time has a quad injury.
He expects to be at the level of rivals Mo Farah and Galen Rupp.
Forty eight athletes from 14 countries will take part.
The race will include five of the six marathoners from the 2012 U.S. Olympic team.
A huge bonus is up for grabs in the half marathon.
Injuries force the fastest American of all-time out of the November 4 race.
He is looking to pick up a sponsor with a decent showing in New York this November.
The were tears of joy and sadness amongst the 105 competitors.