AET: Reds 0 (Reds win 5-4 on penalties)
After two hours of football and no goals, it took an intense penalty shootout - 18 penalties in total - to separate Barnsley and Scunthorpe in the first hurdle of the Capital One Cup.
Chris O'Grady scored the winning spot-kick after Luke Steele made three saves and also missed his own penalty.
On five minutes the Reds registered the first shot of the tie but O'Grady could only drag his effort straight at Slocombe after he did well to bring down Dawson's ball over the top.
After Dagnall teed Mellis up to shoot wide, O'Brien turned on the skill before bursting into the area but his cross was cleared almost unwittingly by the Iron defence.
Former Tykes loanee Deon Burton fizzed a shot over from distance from the right-hand channel as the visitors looked more than capable with the ball.
On 22 minutes a series of efforts by the Iron were actually thwarted by their own man Burton in the area as they looked to squeeze in the opener.
With half an hour gone, a path to goal opened up for Perkins and his deflected effort almost dipped in but for a great save from Slocombe.
A reaction was expected from the Reds but it was, in fact, the visitors who went closer to breaking the deadlock but for a lack of power in front of goal.
The introduction of Scotland on 55 minutes added the impetus Barnsley craved, and the Reds got a response from the home crowd after they began attacking with real purpose. Dagnall took a neat touch before firing just over from a tight angle as he searched for a goal against his former employers.
An injury to Martin Cranie forced the centre-half off, meaning an introduction for Scott Wiseman into the backline two minutes past the hour.
Dagnall went inches wide from finding the bottom corner on 65 minutes when he struck low after latching onto O'Grady's dink into the box.
Scunthorpe were throwing everything in the way of what Barnsley had to offer as a couple of efforts from O'Grady and Dagnall were blocked in the box.
With nine minutes of normal time left the Reds had their last throw of the dice as Cywka replaced Kennedy.
Barnsley were really turning up the heat with Cywka instrumental down the left as the clock ticked down. The Iron were hanging on in hope of extra time.
Three minutes of additional time was indicated but neither side could break the deadlock.
Dagnall had three attempts, two blocked in the first half of extra time as the Iron continued to cling on, but still they were holding out well. At the other end Sparrow scooped over when well positioned after picking up the ball from the right.
In the second period, a glorious chance fell for O'Grady but he sliced wide after swinging a boot at O'Brien's cross.
Tomasz Cywka thumped a 25 yard free-kick at goal but Slocombe was equal to it as he palmed over for a corner.
Barnsley's number one came to his side's rescue when Godden went one-on-one down the right but Steele spread himself well to deny him a certain goal.
Scunthorpe - Hawkridge: MISS
Barnsley - Dagnall: MISS
Scunthorpe - Collins: GOAL
Barnsley - Scotland: MISS
Scunthorpe - Sparrow: MISS
Barnsley - Cywka: GOAL
Scunthorpe - Iwelumo: GOAL
Barnsley - Dawson: GOAL
Scunthorpe - Godden: GOAL
Barnsley - Perkins: GOAL
Scunthorpe - Welsh: MISS
Barnsley - Steele: MISS
Scunthorpe - Slocombe: MISS
Barnsley - O'Brien: MISS
Scunthorpe - Mirfin: GOAL
Barnsley - Golbourne: GOAL
Scunthorpe - Canavan: MISS
Barnsley - O'Grady: GOAL
Reds: Steele, Golbourne, Kennedy (Cywka 81), Cranie (Wiseman 62), O'Brien, Dawson, O'Grady, Perkins, Dagnall, Mellis (Scotland 55), M'voto.
Subs: Alnwick, Hassell, McNulty, Cofie.
Scunthorpe Utd: Slocombe, Ribeiro, Dawson, McAllister (Godden 78), Mirfin, Canavan, Sparrow, Burton (Iwelumo 72), Hawkridge, Collins, Winnall (Welsh 71).
Subs: Severn, Waterfall, Howe, Hornsey.
Referee: Paul Tierney
Assistant Referees: Alf Greenwood & Ross Joyce.
Fourth Official: David Storrie.
Attendance: 5238 (496 away)
Man of the match - sponsored by Napoleon's - Jim O'Brien.