The Pilgrims led 2-0 just after half-time, courtesy of goals from Ken Aboh and Lennon Wheeldon, but the Blues roared back into contention after 70 minutes with Connor Reilly scoring a brace, either side of Finn McGreevy's leveller.

United had made seven changes ahead of kick-off, with Luke Faxon and George Ward handed their competitive debuts for the Pilgrims after unused substitute outings against Aldershot Town and Solihull Moors.

The Pilgrims took a 37th minute lead when ABOH cut infield to bury a drive into the far corner of Will O'Sullivan's net. The Blues keeper had already denied Wheeldon and Kai Mauro by this point.

United doubled their advantage five minutes after the break when WHEELDON shifted the ball inside before beating O'Sullivan with a firm drive from 18 yards.

Two of United's senior players had departed at half-time, before three more followed before the mid-point of the second half - and Birmingham's comeback gathered momentum.

REILLY, only on the pitch for nine minutes, rolled home Blues' first goal in the 70th minute and McGREEVY levelled five minutes later.

REILLY survived a marginal offside call to run through and fire Birmingham's winner two minutes into stoppage time - although the visitors still needed a big save from O'Sullivan to deny United sub Liam Clayton at the death.

Boston (3-4-2-1): Luke Faxon; George Ward, Jake Rooney, Connor Teale (Lenell John-Lewis 67); Sai Sachdev (Caleb McBride 46), Ben Hammond, Gavan Holohan (Lewis Shipley 63), Kai Mauro; Jack Holmes, Ken Aboh (Stephen Pereira 46); Lennon Wheeldon (Liam Clayton 63). Subs (not used): Arjan Raikhy, Louis Chadwick (gk).

Birmingham (4-2-3-1): Will O'Sullivan; Riquelme Thompson-Jones, Billy Burrell (Blake Campbell 77), Jack Quirk, Curran Chahal; Cobi Maddox, Taha Elmansuri (Junior Wilson 70); Salif Bamba Biol (Dynaeo Martin-Moore 61), Menzi Mazwi, Finn McGreevy; Tobey Ugorji (Connor Reilly 61). Sub (not used): Tyrese Warmington (gk).

Referee: Jamie Robinson.

Attendance: 425.

PIC: Chris Bray.