We relive their humorous rivalry video from 2010.
The two-time Olympian will be moving back to Boulder, Colo., on Jan. 1.
She set a world's best 12K time last weekend in Alexandria, Virginia.
Huddle and Flanagan notched the two fastest 12K road running performances in history.
Shalane Flanagan, Molly Huddle and Emily Infeld will lead the way in the inaugural event.
There were some fast races on the day before the New York City Marathon!
Course-record finishes light up the Big Apple streets on the day before the New York City Marathon.
The race takes place in Central Park the day before the NYC Marathon.
American Shalane Flanagan was eighth.
Shalane's mother and father were serious runners back in the day.