Longford champions Emmet Og progressed to a semi-final against Portlaoise following an impressive victory at Pearse Park.
Emmet Og held a three-point cushion at the interval and then turned the heat up with two well-taken goals in the early minutes of the second half.
O'Mahonys did try to mount a credible fightback when they hit three points over a five-minute spell, but Emmet Og had enough firepower and wrapped up the contest with a volley of scores.
The home side got off to a bright start when they registered a brace of points in the opening five minutes. Michael Quinn converted a '45' while Sean McCormack found the target from a placed ball.
O'Mahonys broke their duck moments later when Stephen McGowan set up Jake Regan and he duly obliged off the right peg. Regan was the best of O'Mahonys' forward pack and he drew parity in the 12th minute with a fisted point.
Emmet Og's full-forward line could do no wrong and Mark Hughes put them back into the lead when he split the posts from 35 metres.
The hosts continued to dominate after the break and bagged two second-half goals inside the opening three minutes.
Simon Kiernan gave their loyal supporters something the cheer about when he fisted home an excellent goal over the head of the O'Mahonys netminder Marcus Brennan. The ball was lobbed into the danger zone by Sean McCormack and the towering midfielder was in the perfect position to flick home into the roof of the net.
Seconds later, Brennan was picking the ball out of his net again. Quinn capitalised on a mistake from corner-back Ian Matthews, who laid up his pass too short to Gary O'Brien and Quinn intercepted to side-foot his shot into the left-hand corner.
The visitors finally registered their first point of the second half in the 45th minute. Jake Regan slotted over a well taken '45'. Second-half sub David Bray then reduced the deficit further when he nailed an acute placed ball.
Emmet Og restored order when Sean McCormack concluded his tally with a close-range free and brothers Denis and Ronan McGoldrick put the cherry on the cake with another two points.
Scorers -- Emmet Og: M Quinn 1-1 ('45'), S Kiernan 1-0, D McGoldrick, S McCormack (2f) 0-3 each, R McGoldrick 0-2, D Mimnagh, E Clarke, M Hughes, J McCormack 0-1 each . O'Mahonys: J Regan 0-3 ('45'), S Bray 0-2 (1f), P Smyth, S Gillespie, D Bray (1f) 0-1 each.
Emmet Og -- C Burns; D Bennett, P McCormack, D Keogh; S Dowd, J McCormack, M Quinn; P Thompson, S Kiernan; D McCormack, R McGoldrick, D Minmagh; E Clarke, M Hughes, S McCormack. Sub: R Keogh for S Dowd (inj 39).
Navan O'Mahonys -- M Brennan; S O'Toole, N McKeigue, I Matthews; B Dillion, S Crosby, G O'Brien; D Moran, C McGuinness; P Smith, H Finnegan, S Gillespie; J Regan, S Bray, S McGowan. Subs: D Bray for H Finnegan (h-t), S Keating for B Dillon (h-t), Barry Regan for D Moran (35), C Reilly for S McGowan (44), D Smyth for J Regan (51).
Ref -- G McCormack (Dublin).