Dumbarton struck late to break Cumnock hearts at Townhead Park tonight.
Skipper Gregor Buchanan and Finlay Gray bagged goals in the 14 minutes just as Brian McGinty's men looked on course to force extra time following a rousing second half show.
Cumnock's Ryan Carnwath had cancelled out Stuart Carswell's first half opener as the hosts put up a bold display in front of the BBC Scotland cameras.
But it wasn't to be as the League Two side edged over the line and into the hat for round three.
'Nock had almost been caught cold in the first minute when Joe McKee glanced a header just wide from 12 yards.
The hosts settled after that early scare but both sides struggled to find rhythm with clearcut chances at a premium.
It took 20 minutes for the Sons to get another sight of goal when McKee again went close, this time firing wide a Kalvin Orsi cutback.
But the visitors got their breakthrough soon after when that man McKee won a spot kick after Carnwath was adjudged to have struck him in the face inside the box. And Carswell stepped up to ram home the penalty.
McKee was denied by Jamie Barclay soon after as the Sons threatened to turn the screw but the 'Nock number one was equal to the task.
But McGinty's men came flying out of the traps after half time and got back on level terms when Carnwath gained quick redemption with a tidy finish at the backpost.
Jordan Moore then lashed a half volley just wide on the run and sub Callan Veitch stung the palms of Brett Long as 'Nock threatened to turn the game on its head.
At the other end, Ryan Wallace fired over in space before Dumbarton broke Cumnock hearts with 14 minutes to go.
The home side couldn't clear a corner and when Ross McLean returned the ball into the box, skipper Buchanan headed home.
But 'Nock weren't prepared to lie down and Greg Ferry glanced a Mark McLennan free kick inches wide as they threw everything at an equaliser.
However, they were caught out again on the break in stoppage time as Gray rounded Barclay to put the seal on the win.
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