Goals by Luke Avis and Spencer Tinkler earned the Tigers a 2-0 semi-final success against cup holders Leicester Nirvana at Carter’s Park and they will now meet Deeping Rangers or Daventry Town in the final.
Holbeach should have won by a bigger margin to match the 4-0 home win over Nirvana in September.
Billy Smith missed three opportunities before the deadlock was broken by Avis as his left-wing cross floated inside the far post.
At the start of the second period, James Tricks and Jack Smith wasted golden chances to increase the lead.
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The lead was finally doubled from a set-piece. Joe Braithwaite’s free-kick was nodded on by Tricks and the ball was knocked in from close range by Tinkler.
Holbeach were beaten on penalties in the 2016 final by Peterborough Sports.