The Pilgrims' under-19s were beaten 1-0 at Egerton Youth Club by Altrincham.
Isaac Mannion scored the only goal of the game for the hosts after 15 minutes.
Boston: Zach Marsh, Finley Hipkin, Jake Thompson (Dexter Tomlinson 46), Toby Cotton, Charlie Brooks, Kirils Snikeris (Tyreece Keating 60), Oliver Callaby (Denis Matei 65), Josh Panton (Sean Bray-Smith 46), Will Pettitt, Rueben Fogg, Daniel Bridges. Sub (not used): Austin Barker (gk).
Referee: Hong Kai Shu.