Declan McManus scored twice as holders The New Saints left it late to avoid a Welsh Cup giant-killing at Briton Ferry Llansawel.
Ferry are setting the pace at the top of JD Cymru South and took a shock lead early in the second half through Tom Walter’s stunning drive.
The noisy Old Road crowd were eyeing a famous win against a team unbeaten in the cup since March 2018.
But quadruple-cashing TNS were unfazed as they ran out 5-1 winners.
Two goals in eight minutes by Ben Clarke and McManus put them ahead before Ryan Brobbel, McManus and Brad Young all netted in the final 13 minutes.
Assistant manager Chris Seargeant said: “It was a bit of a scare just after half-time. We knew the type of game it would be with them putting bodies behind the ball and limiting the space on this small pitch.
“It was an old-fashioned cup tie, a decent crowd looking at a giant-killing.
“But the lads showed a great mentality, conceding the goal didn’t get them down and we always felt there would be chances late on as they tired.
“We’re used to having a target on us, especially with the run we’re on. Everyone wants to be the team to bring that run to an end but we carry on.”
Flint Mountain will hope to continue their remarkable cup run to the semi-finals.
The Ardal North West League side are the lowest-ranked team left in the competition and head to Bala Town on Saturday 17 February.
Elsewhere Colwyn Bay travel to Cardiff Met and Buckley Town host Connah’s Quay.