Horncastle Town edged it against second placed Grimsby Borough Reserves in the Balcan Lighting Supplies Lincolnshire League Challenge Cup quarter-finals on Saturday.
Meanwhile, Brigg Town Reserves needed penalties to see off bottom club Harrowby United Reserves, Skegness Town completed a league and cup treble over Immingham Town, and Nettleham stung local rivals and holders Hykeham Town.
With the top four of the in cup action, the chasing pack had a chance to close the gap.
Louth Town made the most ground, climbing into fifth place thanks to a solitary goal victory over Sleaford Sports Amateurs.
Lincoln Moorlands Railway earned the local bragging rights when they hit four goals past Newark Road rivals Ruston Sports, while Sleaford Town Reserves climbed onto the shoulders of Market Rasen Town with a single goal victory at Rase Park.
Wyberton bagged their first victory since the departure of former manager Gary Frost with a 2-0 success at CGB Humbertherm.
Grimsby Borough Reserves 0
Horncastle Town 1
The tie of the last eight was arguably that at Lucarly’s, where Grimsby Borough’s second string welcomed Horncastle Town.
After receiving a bye in the last round, following the withdrawal of Cleethorpes Town’s Development Squad, the Wongers needed just the one goal to secure their place in the semi-finals.
It came from Michael Harness, Town’s leading scorer, who made it 17 from 14 appearances in a Horncastle shirt this season.
Horncastle will host Skegness Town in the semi-finals after the seasiders overcame Immingham Town 3-2 at home.
Results: CGB Humbertherm 0 Wyberton 2; Lincoln Moorlands Railway 4 Ruston Sports 0; Louth Town 1 Sleaford Sports Amateurs 0; Market Rasen Town 0 Sleaford Town Reserves 1. Challenge Cup: Grimsby Borough Reserves 0 Horncastle Town 1; Harrowby United Reserves 1 Brigg Town Reserves 1 aet (Brigg won 2-0 on penalties); Hykeham Town 1 Nettleham 3; Skegness Town 3 Immingham Town 2.