Town 1 Grimsby 0 - Report and pictures
Abu Ogogo's superb last-gasp strike saw Shrewsbury Town squeeze past Grimsby to keep their hopes of an FA Cup run alive.
Ogogo struck in the second minute of time added on at the end of the game to finally separate the sides after 180 minutes of goalless action.
But Micky Mellon's side were lucky to have got their place in the hat for the third round at Championship side Cardiff.
Until Sullay Kaikai's shot blocked by keeper James McKeown in the move that produced the goal, Salop failed to force a serious save and didn't even have a corner, to the Mariners' nine, with the Conference side the better side in both ties.
Craig Clay missed a golden chance in the first half for Grimsby when sub Omar Bogle fired over.
Mark Halstead kept Mellon's side in it with a superb save in the 76th minute to somehow tip over Padraig Amond's point-blank header, while Josh Gowling nodded wide from a good chance.
For their part, Shrewsbury had three off-target efforts from Kaikai from distance and Junior Brown curled inches off target.
There were two changes to the Salop team from Saturday's 1-1 draw at Peterborough.
Tyrone Barnett earned a promotion to the starting line-up after scoring against his old club in a lively performance off the bench, while at the back, Zak Whitbread ended his injury-enforced replaced Nat Knight-Percival, who dropped to the bench.
Among the substitutes there was a surprise appearance for Ian Black, who had been ruled out through suspension after picking up his fifth booking on Saturday.
Black was benefitting from a revised amnesty date in the suspension rule, brought forward from February to December.
Action was slow to get going but Salop settled quickly and had plenty of possession in the early stages.
But it was a fairly forgettable first half thin on entertainment and goalmouth incident.
Kaikai had half chances from long range at the start and end of the half.
First his well-hit set-piece failed to dip anywhere near enough and fizzed over after 10 minutes, then with the last kick of the first period, he cut inside but his blockbuster arrowed just too high and wide.
Scott Vernon was next to try his luck with a quarter of an hour gone, but his first-time placed effort was too close to keeper McKeown to trouble him.
Kaikai went for goal again on 19 minutes, but his skidding drive flew wide after cutting inside.
Thankfully for Shrewsbury, Grimsby weren't at the tempo they showed at Blundell Park, and they suffered a disruption midway through the first half when they lost striker Jon-Paul Pittman to injury.
Pittman went off holding his right arm awkwardly after being hurt falling following a challenge by Anthony Gerrard, with Bogle the replacement.
But the Mariners provided the hosts with a let-off in the 25th minute from the best opening of the first period.
Whitbread missed Conor Townsend's cross and Clay should have done better than blaze well over the bar bearing down on goal.
Gerrard was again defending admirably at the back but Salop lacked the urgency going forwards to trouble the visitors.
Their cause wasn't helped by Jermaine Grandison going off in the 37th minute after signalling to the bench that he was in trouble, with Dom Smith coming on.
Bogle flashed another warning across their bows in the first minute of time added on before half-time when he turned and fired over after Aristote Nsiala headed a free kick back back across into the danger area.
Shrewsbury started the second half with more urgency as they looked to take the lead.
Junior Brown crossed and Nsiala cleared, then Kaikai centred and Smith flashed an angled volley straight at McKeown from the corner of the box.
But the hosts suffered a further disruption at the back eight minutes after the break when Whitbread was led off.
Knight-Percival came on and his first task was to try to defend a corner, but Gowling got there first only to glance well wide.
The Mariners lacked nothing in spirit and continued to come at Salop, Townsend curling over a free kick just before the hour.
There was little between the teams and Salop hit back through Brown, who cut inside Nathan Arnold before curling inches wide of the far post on 65.
Action became more urgent and frantic as the prospect of extra-time began to loom.
Halstead kept Shrewsbury in the game in the 76th minute with a breathtaking save to tip over Amond's point-blank header from Townsend's cross.
Mellon's side failed to clear the resulting corner and all of a sudden Bogle was threatening to bear down on goal only for Brown to appear from nowhere to hack clear.
Grimsby had grown in confidence as the second half wore on and they continued to force the pressure.
Gowling could have won in with four minutes left but headed wide from Townsend's corner.
But just when it seemed the visitors were poised to score, Shrewsbury suddenly hit back to win the tie in stunning fashion.
Kaikai broke and ran at the last man before his left-foot drive was parried by McKeown diving to his right.
The rebound bounced high into the air, James Collins controlled it with his back to goal and teed up Ogogo on the edge of the box and the midfielder crashed a superb volley with the outside of his right foot into the keeper's bottom left-hand corner.
Town (4-4-2): HALSTEAD 8; Grandison 6 (Smith 37), Gerrard 8, Whitbread 6 (Knight-Percival 53, 6), Brown 6; Ogogo 7, Lawrence 7, Kaikai 7, Vernon 6; Collins 5, Barnett 5 (Black 77, 5).
Subs not used: Whalley, McAlinden, Clark, Burton (gk).
Grimsby (4-4-2): McKeown; Tait, Nsiala, Gowling, Townsend; Arnold, Disley, Clay, Monkhouse; Pittman (Bogle 23), Amond.
Subs not used: Robertson, Brown, Pearson, Henderson, Alabi, Warrington (gk).
Referee: Dean Whitestone (Northants).
Attendance: 2,730 (286 Grimsby fans).