Club secretary Stuart Manning said Moulton Harrox “certainly deserved” Saturday’s victory against Appleby Frodingham.
Late second-half goals from Louis Steadman and substitute Daniel Lambe-Hyner secured progress to the Lincolnshire FA Junior Cup semi-finals.
The tie was deadlocked until before Steadman scored with a stunning free-kick deep into the second half.
Substitue Lambe-Hyner ensured the win with a late chip after breaking past the Appleby defence.
Manning said: “We missed three or four really good chances to go ahead.
“We knew how strong Appleby were going to be and that we would have to be at our best to beat them.
“Keeping a clean sheet was also very pleasing.
“Our back four was solid all game and our keeper barely had a save to make. Against a strong team like Appleby, that is very impressive.”
The win means Harrox will meet Lincoln Moorlands Railway in the semi-finals. The home tie will be played on Saturday, February 3.
Harrox are not in league action again until January 20 when they travel to lowly Whittlesey.
We knew how strong Appleby were going to be and that we would have to be at our best to beat them.Stuart Manning
Second-placed Stamford Lions overcame Peterborough Sports Reserves 3-0 to close the gap at the top of the table to five points on Saturday.
Wyberton beat Coningsby 5-1 to progress to the Junior Cup semi-finals. They will meet either Tetney Rovers or Shape Changers.