Boston slammed in five past non-league Hornchurch to secure FA Cup victory.
The visitors took a shock early lead as Steve Castle's free-kick sneaked in but Boston levelled when Lee Thompson took advantage of a goalmouth scramble.
Tom McManus scored from close-range before Hornchurch had Simon Downer sent off and McManus then converted Jason Lee's pass, but Terry Everett replied.
David Noble fired in from a Thompson pass and finally Paul Ellender nodded in to complete the rout.
Boston Utd: Abbey, West, Beevers, Ellender, McCann, Thompson, Noble (Rusk 90), Greaves, Thomas, Kirk (McManus 35), Lee (Norris 90).
Subs Not Used: Strong, Melton.
Goals: Thompson 48, McManus 49, 67, Noble 81, Ellender 89.
Hornchurch: Baruwa, Clancy, Popovic, Downer, Deen, Penn, Castle (Locke 55), Shipp, Douglas (Everett 54), Huke (Peters 45), Sigere.
Subs Not Used: Shepard, McShane.
Sent Off: Downer (51).
Booked: Baruwa, Clancy.
Goals: Castle 4, Everett 78.
Ref: R Olivier (W Midlands).