Deeping Rangers left empty-handed after wasting the chances that came their way while Harborough Town punished them by taking one of their few opportunities.
The Bees played with the benefit of the wind in the first half, although it was Deeping who had the better share of the possession with both sides rarely threatening to break down their opponents.
A free-kick from halfway by Michael Duroe saw the wind take the ball on a different path and force visiting keeper Danny Bircham scrambling backwards to stop the ball crossing the line.
The home side made the decisive breakthrough on 25 minutes. A clearance from defence found Danny Wright on halfway, he turned and sent Jordan Crawford free down the right where he got into the box before blasting his shot past the oncoming Bircham.
A defensive mix-up between Rangers pair Luke Hunnings and Jack Cotton saw a chance for Crawford who shot straight at Bircham.
Rangers’ Jason Kilbride tried his luck from 25 yards but home keeper Glen Giles saved easily, Kilbride burst from his half, played a one-two with Scott Coupland to deliver a defence-splitting pass to free Dan Flack to the edge of the box but his shot was straight at Giles.
The Bees almost doubled their advantage on the stroke of half-time when Crawford sent in a good cross into the box with the arriving Jack Burrows narrowly away from getting a touch.
Deeping went on the offensive from the start of the second half. Coupland fed Flack who sent in a cross from the touchline that just evaded the arriving Kilbride, Coupland was in the home box to see his shot well saved by Giles who produced an even better save as the ball fell to Kilbride who shot first time.
The power of Rangers skipper David Burton-Jones won the ball and released Flack who found Scott Mooney to fire straight at Giles.
A rare home attack saw Crawford free down the right only to be thwarted by the recovering Tom Smith.
Rangers substitute Jezz Goldson-Williams’ quick free-kick set Flack free, his pull-back set a shooting chance for Coupland to test Giles, Burton-Jones’ superb ball released Flack who cut the ball back into the path of Mooney whose shot was hampered by the challenge of home skipper Ben Williams.
Flack’s free-kick caused a scramble in the home box with the ball finally being hacked away for a corner.
The lively Crawford was in behind the vsitiing defence again to bring a good low save from Bircham while at the other end a wayward clearance from Callum Milne was rescued by a good challenge from Williams.
With additional time being played Kilbride sent in a swirling cross that Giles had to tip over from under the bar. From the Coupland corner Spencer Tinkler saw his header rebound from the crossbar for Mooney head over under the challenge.
Deeping: Bircham, Porter (sub Goldson-Williams 67 mins), Smith (sub Bird 83 mins), Burton-Jones, Cotton, Hunnings, Flack, Tinkler, Mooney, Coupland, Kilbride. Subs not used: Carter, Marsden.
Deeping are at home to Boston Town on Tuesday night in the Lincolnshire FA Senior Trophy quarter-final.