AIRDRIE United survived a torrid second half in a classic, old-fashioned cup tie at Bellsdale, to clinch a Scottish Cup fourth-round visit to Morton.
Juniors Beith went down with all guns blazing, after giving their Second Division guests a four-goal start, then the fright of their lives with a magnificent fightback. Indeed, had referee Brian Colvin not ruled that it had been ball to hand when United's Eddie Forrest handled in the final minute, who knows what might have happened.
Playing up the notorious Bellsdale slope, Airdrie might have thought they had the game won after a one-sided first half. Scott Gemmill's fifth-minute opener steadied the senior side's nerves; Jamie Stevenson added a second seven minutes later and, when Gemmill struck again just before the break, it looked all over.
"I decided at half-time, we might as well have a go," said Beith manager Johnny Miller.
"We went to three up front, narrowed the midfield and asked our full backs to bomb forward. They caught us cold, we didn't get going before the break, but I'm so proud of the way the guys battled back after the break."
United made it 4-0 two minutes after the break, Ryan McCord rising to power home a header from a Jamie Bain cross.
But Beith refused to crumble and, on the hour, on-loan Hearts youngster Mark Ridgers had to make a super save from Beith sub Stephen O'Keane. But, just a couple of minutes later, O'Keane rose majestically at the back post to head home a pin-point Martin McGarvey cross to complete a scintillating length-of-the-park counter-attack from the Juniors.
In 66 minutes, Airdrie nerves were jangling as the second half-time sub, John Craig, fired home a terrific 25-yard free kick to further encourage the home team.
Beith had a let-off when Stevenson rattled the junction of cross-bar and upright from 20 yards two minutes later, but, back came Beith and Tony Fraser emphasised their uncertainty at the back post when he slid home a third goal, 11 minutes from time.
Not even the red-carding of skipper Bryan McKeown, for upending Gemmill as he seemed set to complete his hat-trick, in 81 minutes, could douse the Beith fire.
But, after that late penalty call went against Beith, United saw the game out for victory.
"I thought at half-time we had it won but all credit to Beith for their fight-back. We panicked and made some silly mistakes, but the bottom line is, we're through," said a relieved Jimmy Boyle, the Airdrie manager.
Beith: Robertson, Carruth (Fraser 46), Staunton, McCulloch, Sheridan, Bradley, McKeown, McGarvey, Reid (Craig 55), Stewart (O'Keane 46), McLean.Subs not used: Wilson, O'Neill.
Airdrie United: Ridgers; Bain, Grant, Forrest, Gibson, Devlin, Johnston, Fisher, Gemmill (Muir 90), McCord (Donnelly 60), Stevenson (Lovering 88).
Referee: B Colvin.