The Swans' Carling Cup campaign was brought to an end following an extra-time defeat at the hands of Scunthorpe.
Nial Canavan had given the visitors an early lead but a strong second-half performance delivered a deserved Stephen Dobbie leveller late on.
Garry Monk was dismissed minutes later and as the game went into extra-time the Iron were awarded a penalty which Gary Hooper converted.
A frantic finish also saw Gorka Pintado and Angel Rangel sent off while Dobbie was withdrawn through injury.
Manager Paulo Sousa handed young goalkeeper David Cornell his competitive debut in a Swansea City shirt.
The 18-year-old shot stopper replaced Dorus de Vries between the sticks while Marcos Painter returned to the defence 10 months after starting his last match.
New recruit Besian Idrizaj, meanwhile, was named amongst the substitutes.
Swans: David Cornell; Angel Rangel, Alan Tate, Garry Monk(C), Marcos Painter; Jordi Lopez (Besian Idrizaj, 78'), Leon Britton, Nathan Dyer, Kerry Morgan (Mark Gower, 60'), Chad Bond (Stephen Dobbie, 46'); Gorka Pintado
Not Used:Dorus de Vries (GK), Shaun MacDonald, Ashley Williams, Matty Collins.
Scunthorpe: Joe Murphy (C), David Mirfin, Nial Canavan, Jordan Spence, Marcus Williams, Matthew Sparrow, Josh Wright, Sam Togwell (Gary Hooper, 87'), Martyn Woolford (Garry Thompson, 76'), Paul Hayes, Jonathan Forte (Michael O'Connor, 64').
Not Used: Joshua Lillis, Ian Morris, Adam Boyes, Cliff Byrne.
Attendance: 7,321 Away: 86
Referee: J Linington (Isle of White)
It took some time for both sides to to create anything of note with rookie 'keeper David Cornell making a confident stop after five minutes.
The Swans burst into life in the proceeding minutes with Nathan Dyer showing the class he has in each game to date to get past Scunthorpe's unsuspecting left-back, Marcus Williams.
He was unlucky not to find Kerry Morgan with a deep cross while a one-two with Gorka Pintado almost paid off only for the pacy winger to put too much weight on the returned ball.
Chad Bond, who only made his Football League debut at Coventry, won his side a corner on 10 minutes - Jordi Lopez crossed in and Garry Monk's header was tipped over by Joe Murphy.
Youngster Cornell was forced into saving from Paul Hayes two minutes later, forcing an Iron corner, but from the resulting cross Nial Canavan connected with his head to power home the game's opening goal.
The Lincolnshire outfit were brimming with confidence and on 17 minutes threatened to add a second with Martyn Woolford drilling low and inches wide of the post.
But the home side came increasingly close to levelling three minutes later - a strong pass from Alan Tate at the back picked out Kerry Morgan and the youngster showed great skill to take the ball down and forward before drilling inches over the top of Murphy's goal.
Jordi Lopez saw his low drive stopped by Murphy midway through the first-half while Cornell made a fine save low to his left, pushing the ball wide, from Woolford's 31st minute strike.
A sweeping move from the back that started with Alan Tate saw Angel Rangel stride forward before finding Morgan on the left wing, he cut inside Marcus Williams and shot straight into the arms of Murphy, while a Lopez corner seven minutes before the break was narrowly missed by Monk inside the area.
Moments later and Rangel picked out Gorka Pintado 10-yards from goal but the strikers mis-hit effort bobbled wide to the frustration of the Basque front-man.
The hosts did up the tempo in the closing stages and Alan Tate's low drive inches past the post was the closest they came to drawing level.
Half-Time: Swans 0 Scunthorpe 1
Stephen Dobbie was introduced at the break in place of Chad Bond and within 60 seconds of the re-start Pintado won his side a free-kick in dangerous territory after being brought down by Marcus Williams.
The set-piece was awarded a yard outside the area, Marcos Painter stepped up to take it but his weak effort was easily cleared by the Scunthorpe defence.;
Substitute Dobbie almost grabbed a leveller moments later, turning his marker and dragged his shot just past the post, while the same player saw his effort deflect wide for a corner following fine build-up by Rangel and Lopez.
Nathan Dyer came even closer 11 minutes into the second period as he fired inches over the top of goal after Rangel had skipped past three players as he cut inside from the right.
A second Swansea change was made on the hour with Mark Gower coming on for Kerry Morgan in a straight swap out wide.
Dobbie was looking lively alongside Pintado in attack and the Scotsman had the Swans' best chance of the night 15 minutes from the end as he cracked a shot against the crossbar,
Neat one-touch play between Britton and Gower set-up the striker who took a touch before firing past Murphy only to see his effort bounce over.
Paulo made his third and final substitution 11 minutes before time with Besian Idrizaj coming on for Jordi Lopez, and the Austrian youngster made an immediate impact by setting up the Swans' leveller.
The 21-year-old played in fellow sub Dobbie and with a wicked low drive found the bottom corner to score a deserved leveller for the home side.
But joy soon turned to sorrow as the Swans were reduced to 10 men with five minutes left on the clock, skipper Garry Monk seeing red after he was alleged to have clashed heads with Iron sub Michael O'Connor.
Goal hero Dobbie sent Dyer on his way towards goal with 90 seconds left on the clock, the ball was cleared at his feet to Idrizaj whose attempted lob was easily gathered by Murphy.
And with the game heading into extra-time Gorka Pintado had a glorious chance deep into injury-time to win it for the Swans but he couldn't connect with Idrizaj's flick on from close-range.
Full-Time: Swans 1 Scunthorpe 1
The referee got extra proceedings underway and within a minute of the re-start Mark Gower found his way through on goal but fired straight into the hands of the visiting 'keeper.
Pintado also found himself one-on-one with Murphy but again the shot was fired straight at the Iron skipper, while Idrizaj saw his free-kick stopped by the goalkeeper.
Things did get worse for the hosts, though, as the number of players reduced to nine - but this time it wasn't a dismissal by the referee, striker Stephen Dobbie was forced off after taking Josh Wright's boot to his stomach.
Mark Gower was inches away from putting the Swans in front in first-half stoppage time but fired over the top from 25-yards.
Half-Time (ET): Swans 1 Scunthorpe 1
The 11-men of Scunthorpe started the strongest in the second period and they piled pressure on the home penalty area.
David Cornell was called into action to make two saves but, five minutes in, the referee awarded Scunthorpe a penalty.
Alan Tate was the Swans player penalised after he was adjudged to have handled Paul Hayes shot, substitute Gary Hooper stepped up to take the kick which he fired past the young 'keeper.
Idrizaj attempted to offer an instant reply but his acrobatic effort from Rangel's long throw flew way over the top of goal.
And just when you didn't think it could get any worse, the Swans were down to eight - this time a second dismissal. Gorka Pintado shown a second yellow for a challenge on Michael O'Connor.
Angel Rangel followed straight after, red carded for another challenge.
Tempered flared during the closing stages but Scunthorpe held on to book their place in round three of competition.