Aaron Eyett capped a man-of-the-match display with a goal against his former club to finally settle Wednesday night’s derby.
The ex-Boston Town winger cut inside from the left flank and hit a right-foot drive which took a deflection past keeper James Lambley to double Holbeach United’s advantage.
The Tigers were forced to wait until that key moment 14 minutes from full-time to book their place in the Knockout Cup quarter-finals.
They led courtesy of Jordan Thomas’ strike on 13 minutes and should have been further ahead before Eyett made it 2-0.
Lambley got a hand to the 20-yard drive from Thomas but couldn’t stop the ball going into the bottom corner of the net.
Alex Beck twice missed the target for the Poachers but Andrew Tidswell and Josh Ford wasted better chances at the other end.
After the break skipper Jamie Steven’s header was cleared off the line and Ford was denied by Lambley.
It took 87 minutes for Boston to force a save from Rick Drury who superbly pushed over Curtis Revell’s effort.
Two weeks after the Tigers’ 3-1 league win at Boston, this was another comfortable evening where the two-goal margin of victory really should have been bigger.
4-2-3-1: J Lambley; L Lambley (sub Freeman-Birdass 70 mins), Ashton, M Wood, Parker; Eyes (sub R Ford h-t), D Wood; Smith, Revell, Bayliss; Beck (sub Bevan 73 mins).
4-4-2: Drury; Tinkler, Stevens, N Jackson, A Jackson; Eyett, Tidswell, Warfield (sub Pinner 88 mins), Thomas (sub Treacher 70 mins); J Ford, Clitheroe (sub Jack Smith 76 mins). Subs not used: Walton, Roberts.
Thomas (13 mins, 0-1); Eyett (76 mins, 0-2).
Bayliss (unsporting behaviour); M Wood, Warfield (fouls); J Ford (persistent fouling).
Aaron Eyett - excellent on his return to the DWB Stadium.