Aberdeen, looking to end a 30 year wait for the Scottish Cup, came into the game off the back of their midwinter training camp in Dubai. Derek McInnes made five changes to the side that drew at Hearts before the break, giving an immediate debut to new signing Dylan McGeouch, with Sam Cosgrove, Andrew Considine, Connor McLennan and Niall McGinn all back in the starting XI. Dean Campbell, Curtis Main and Jon Gallagher all moved to the bench, while Zak Vyner missed out from the Hearts game through injury and Lewis Ferguson through suspension.
Dumbarton have had a winter break of their own of sorts, with last weekend's game against Clyde being postponed. Having last played on January 4th in a 3-0 defeat at second placed Falkirk, Jim Duffy made four changes to that side, bringing in Lewis Crawford, Joe McKee, Callum Wilson and PJ Crossan in place of Reghan Tumilty, Stewart Carswell, Conor Scullion and Ryan Tierney, the latter two dropping to their four man bench.
After a slow opening to the game, the first moment to raise the temperature came in the 13th minute when Cosgrove went down under a challenge in the penalty area right in front of the "Red Shed," but the referee waved away his claims for a spot kick.
Two minutes later, a lovely disguised pass from McGeouch almost slotted McLennan in, then almost immediately, the new signing drove in a shot that Brennan handled well at his near post.
The Dons were getting into things now and in the 18th minute, McGinn bent a free kick into the box, Cosgrove was able to get a flick header on it that diverted the ball just round the far post with Brennan scrambling. McGinn's left-wing corner two minutes later almost broke the deadlock, Ash Taylor flinging himself at the ball to bullet a header just over the bar from a dozen yards out.
By now, the game was being played almost exclusively in the Dumbarton half, the visitors getting ten yellow and black shirts behind the ball whenever possible. On 27 minutes, good persistence from McLennan allowed him to get a cross in from the right. Cosgrove's initial shot was blocked but it dropped for Bruce Anderson who shinned his shot over the bar from around the penalty spot. Another corner followed a minute later, Considine well up this time but again, his header was over the bar.
Lovely play between Considine, Funso Ojo and McGinn gave the Northern Irishman a sight of goal, but from out wide on the left, his right footed attempt to bend the ball round Brennan also saw the ball bend wide of the far post.
For all the territorial advantage though, it was a ring rusty looking first half from the Dons. Anderson almost broke the deadlock in the final minute of the half, onto a loose ball, but his shot took a deflection and bobbled harmlessly wide. From the corner, Considine was up again at the back post but Brennan pouched his header easily enough to leave the game deadlocked at the break.
The Dons made a sharp start to the second half, McLennan immediately playing in an early cross, McGinn darting in at the back post but putting the ball back across goal and wide of the target. Moments later, a McGinn corner found Cosgrove on the edge of the box, but he shot into the ground and the ball bounced up nicely for Brennan to save.
Some 51 minutes in and McGinn got a free kick in exactly the same spot as he'd scored against Hearts in the previous game, but this time, he put his shot over the bar. McGinn was the creator a minute later, spearing a cross into the near post, Cosgrove in on it but putting his header wide of goal under pressure from Neill.
McGinn was starting to cause havoc now with his quick feet, winning another corner in the 54th minute and delivering it onto the head of Scott McKenna but once again, his effort was always rising over the bar from six yards out.
Corner number seven was almost decisive in the 57th minute, Taylor up to it at the back post but the massed Dumbarton ranks were able to scramble the ball clear again. The Dons should have been in front in the 63rd minute, McGinn clipping the ball into the box from the left, Anderson coming onto it seven yards out but lifting it over the bar from between the posts.
Ryan Hedges became Aberdeen's first change in the 67th minute, replacing McLennan. Still the Dons couldn't break through the yellow and black wall, Ojo smashing one at goal from 25 yards or more in the 71st minute, Brennan saving well, Anderson poking the rebound wide under pressure from the goalkeeper.
Anderson was denied again a minute later, down at his near post to block his shot from Cosgrove's knock down from Ojo's cross. Zata then came on for Wilson in the 74th minute in Dumbarton's first swap. Two minutes later, the Dons came close again, Cosgrove almost on the end of a low Considine cross through the six-yard box, before Dean Campbell took to the field in place of the impressive debutant McGeouch.
With ten minutes to go, McGinn almost found the net, a 25-yard curler from the edge of the box beating Brenan but just going wide of the far post as Aberdeen continued to knock on the Dumbarton door. A minute later, a good crossfield ball from Anderson found Hedges who cut inside, onto his left foot, but could only fire into the side netting.
The Aberdeen pressure finally bore fruit, Cosgrove hacked down in the box by Quitongo in the 85th minute to give the Dons a penalty, Dumbarton taking an age in protesting the obvious award, Brennan booked for his protests. Sam wasn't affected, sending Brennan the wrong way and giving Aberdeen a 1-0 lead.
The visitors brought on Tierney for Langan in the 88th minute, then Anderson could have settled the game, a free header from a McGinn corner six yards out, but his header was deflected over the bar from six yards out. Anderson, who picked up a knock as he won the header, was then replaced by Gallagher, McGinn putting in a corner and Considine, again, going over the bar with is header. Crossan then made way for Scullion.
The visitors won themselves a corner three minutes into injury time, Cosgrove winning the crucial header as the Dons were able to clear their lines and see themselves through to round five of the competition, finally seeing off their doughty Dumbarton opponents. All credit to the League One side for battling away to the last and producing such a resilient rear-guard action.