Uceny won her third title in four years, while Willis repeated his win from 2013.
Bernard Lagat going after American, world records in rarely run 2,000m event.
Also competing will be Alan Webb, who is retiring from professional running to focus on triathlon
The Olympian set a new facility record of 4:24.54 in the women's mile.
The new Boston-based training group will be made up of elite level U.S. athletes.
The American miler, her coach, and training partners abandoning their English training base.
Garret Heath and Morgan Uceny won at Manchester's Great CityGames.
The Americans bring a strong field to this year's race in the heart of Manhattan.
Most of the pre-meet contenders advanced through the preliminary rounds.