Holders Swansea City are out of the League Cup after a shock third-round defeat by Championship side Birmingham City at St Andrew's.
After a goalless first half, Dan Burn put Blues in front with a header.
A right-footed finish by Matt Green from Chris Burke's cross and a tap-in by Tom Adeyemi gave Lee Clark's side an unassailable lead against their Premier League opponents.
Striker Wilfried Bony replied for Swansea in injury time.
League Cup fourth-round draw
Sunderland v Southampton
Leicester City v Fulham
Birmingham City v Stoke City
Manchester United v Norwich City
Burnley v West Ham United
Arsenal v Chelsea
Tottenham Hotspur v Hull City
Newcastle United v Manchester City
All ties are scheduled to take place in the week commencing 28 October
Manager Michael Laudrup may rue the 10 changes he made to the Swansea side that beat Crystal Palace in the league on Sunday for their first Capital One Cup game since last year's final win over Bradford.
Midfielder Jonjo Shelvey was the only survivor from the 2-0 win over Palace but this was still a Swansea side full of Premier League experience.
There was no evidence in the first half that the holders would succumb to a Birmingham side who had won only one of their previous seven games.
But the home side completely outplayed the Swans after the break and the one disappointment for the 2011 League Cup winners will be that only 7,470 turned up to watch them beat top-tier opponents who have just won 3-0 at Valencia in the Europa League.
The visitors had the first real chance of the game when record signing Bony hit the bar with his header from a Jonathan de Guzman corner before his strike-partner Alejandro Pozuelo pounced on the rebound, only to see his shot hit the post.
Bony wasted a handful of opportunities in the first half but he was also denied by a superb tackle by Birmingham defender Paul Robinson as he bore down on goal.
Swansea's Belgium international Roland Lamah saw his shot saved by the feet of Birmingham goalkeeper Colin Doyle to keep the game goalless at half-time.
But Birmingham looked a different proposition in the second half and led with two goals in four minutes either side of the hour mark.
How times change
Birmingham won the League Cup in 2011 but they were relegated from the Premier League and replaced by Swansea City.
Sloppy defending by Swansea allowed Fulham loanee Burn a free header to score his third goal for Birmingham from a cross by midfielder Paul Caddis.
Green then doubled the home side's lead when striker Green met Mitch Hancox's cross with a superb right-foot finish at the back post to make it 2-0.
The home side then completed the victory with a third goal, nine minutes from time, when midfielder Adeyemi profited from some good work by winger Burke to tap into an open Swansea goal.
Bony scored his sixth goal in nine games for Swansea deep in injury time, but it the Welsh club's cup rein was long over by then.
Birmingham boss Lee Clark:
"I'm absolutely delighted. I think to win a game like that against the quality of opposition we're up against is very satisfying.
"Not only are Swansea the holders but I said before the game that I felt it was the hardest tie we could have got outside the so-called top six, a club that's on the up in everything that they do.
"Even though they made changes I don't think it affects them as they've got a philosophy that runs through the club."
Swansea boss Michael Laudrup:
"I want to go as far as possible in all competitions. We lost the possibility to go far in the competition.
"I have no regrets (about making 10 changes). You could say 10 changes from the last game but five of the players who played here were in the starting XI against Valencia.
"I don't think I'm wrong if I say we could have been four up at half-time.
"And then with Birmingham's first chance they score, and then the other two goals I think there was a little misunderstanding at the back and in the end we lost the game."
Live Text Commentary
Full Time The referee brings the game to a close.90:00 +4:01 Goal scored
Goal! - Wilfried Bony - Birmingham 3 - 1 Swansea Wilfried Bony scores with a header. Birmingham 3-1 Swansea.90:00 +3:44
Corner taken by Wayne Routledge from the right by-line.90:00 +0:36
Wilfried Bony takes a weak shot and missed to the right of the target.90:00 +0:29
Alvaro Vazquez crosses the ball.87:44
Paul Robinson takes the free kick.87:29 Booking
Neil Taylor receives a yellow card.87:06
Jordi Amat challenges Christopher Burke unfairly and gives away a free kick.86:32
Corner taken by Alejandro Pozuelo from the right by-line.86:09
Header at goal by Jose Alberto Canas. Colin Doyle parries the ball away.85:07
Wilfried Bony takes a shot and went wide left of the target.84:35
Leon Britton restarts play with the free kick.84:29
Andrew Shinnie challenges Alejandro Pozuelo unfairly and gives away a free kick.84:28
Andrew Shinnie restarts play with the free kick.82:38 Substitution
Substitution Andrew Shinnie replaces Shane Ferguson.82:05
Alejandro Pozuelo concedes a free kick for a foul on Mitch Hancox.81:25 Substitution
Substitution Wayne Routledge is brought on as a substitute for Roland Lamah.80:30
Assist on the goal came from Christopher Burke.80:30 Goal scored
Goal! - Tom Adeyemi - Birmingham 3 - 0 Swansea Tom Adeyemi slots the ball right footed into the goal. Birmingham 3-0 Swansea.
Direct effort from the free kick comes in from Shane Ferguson and goes over.78:39
Foul by Alejandro Pozuelo on Paul Caddis, free kick awarded.78:28
Wilfried Bony makes a clearance.78:20
Corner from the right by-line taken by Christopher Burke.78:03
Christopher Burke sends in a cross.77:36
Leon Britton takes the free kick.77:26
Unfair challenge on Wilfried Bony by Paul Robinson results in a free kick.76:47
Matt Green takes a shot. A parry by Gerhard Tremmel prevents the goal.76:30
Mitch Hancox takes the free kick.76:18
Free kick awarded for an unfair challenge on Shane Ferguson by Jose Alberto Canas.75:59
Clearance made by Neil Taylor.75:52
Centre by Tom Adeyemi.75:23
Garry Monk makes a clearance.75:17
Corner taken by Christopher Burke from the left by-line.74:59
Corner from the right by-line taken by Christopher Burke.74:39
Centre by Mitch Hancox.72:56
Neil Taylor restarts play with the free kick.72:50
The official flags Christopher Burke offside.72:07 Substitution
Substitution Jose Alberto Canas replaces Jonjo Shelvey.71:47
Jonjo Shelvey has an effort at goal and missed to the left of the net.71:08
Clearance by Dan Burn.71:04
Corner taken by Leon Britton from the left by-line.70:35
Leon Britton restarts play with the free kick.70:29
Free kick awarded for a foul by Matt Green on Leon Britton.70:16
Paul Caddis makes a clearance.69:17
Shot by Jordi Amat cleared the target.68:30
Clearance made by Callum Reilly.67:49
Christopher Burke takes a shot and went wide of the left-hand post.67:42
The ball is sent over by Callum Reilly.64:46
Corner taken by Christopher Burke from the right by-line.64:25
Mitch Hancox takes a shot.63:07 Substitution
Substitution Alvaro Vazquez replaces Jonathan de Guzman.62:40
Jonjo Shelvey takes a shot and went wide of the left-hand upright.61:30
Neil Taylor makes a clearance.61:21
The ball is sent over by Shane Ferguson.60:32
Assist by Mitch Hancox.60:32 Goal scored
Goal! - Matt Green - Birmingham 2 - 0 Swansea Matt Green grabs a goal with a right foot finish. Birmingham 2-0 Swansea.60:26
Mitch Hancox produces a cross.59:10
Free kick taken by Paul Robinson.58:57
Free kick awarded for a foul by Wilfried Bony on Callum Reilly.58:06 Booking
Colin Doyle is booked.57:59
Free kick taken by Colin Doyle.57:41
Dan Burn fouled by Wilfried Bony, the ref awards a free kick.56:57
Jonathan de Guzman takes the free kick.56:49
Callum Reilly gives away a free kick for an unfair challenge on Dwight Tiendalli.56:08
Christopher Burke provided the assist for the goal.56:08 Goal scored
Goal! - Dan Burn - Birmingham 1 - 0 Swansea Dan Burn heads the ball into the goal. Birmingham 1-0 Swansea.55:48
A cross is delivered by Christopher Burke.54:58
Free kick taken by Paul Robinson.54:35
The official flags Jonathan de Guzman offside.53:14
Garry Monk manages to make a clearance.53:07
The ball is delivered by Mitch Hancox.52:14
Gerhard Tremmel takes the free kick.52:02
The assistant referee signals for offside against Matt Green.51:46
Colin Doyle restarts play with the free kick.51:33
The assistant referee flags for offside against Wilfried Bony.49:01
Matt Green takes a shot.48:49
Mitch Hancox makes a clearance.48:44
Roland Lamah crosses the ball.47:37
Christopher Burke delivers the ball.45:01
The second half kicks off.45:00 +2:07 Half time
Half Time The players leave the pitch at half time.45:00 +1:45
Free kick crossed by Shane Ferguson.45:00 +0:19
Leon Britton is booked.45:00 +0:19 Booking
Leon Britton challenges Christopher Burke unfairly and gives away a free kick.43:28
Colin Doyle takes the free kick.43:06
Unfair challenge on Shane Ferguson by Jonathan de Guzman results in a free kick.42:56
Dan Burn makes a clearance.42:50
The ball is crossed by Jonathan de Guzman.42:34
Tom Adeyemi takes a shot. Gerhard Tremmel catches the ball.42:23
Free kick taken by Mitch Hancox.42:14
Dwight Tiendalli challenges Mitch Hancox unfairly and gives away a free kick.41:21
Mitch Hancox crosses the ball.40:24
Roland Lamah has an effort at goal.38:47
The ball is sent over by Wilfried Bony.36:51
Clearance by Garry Monk.36:48
Paul Caddis produces a cross.34:59
Corner taken by Shane Ferguson from the right by-line.34:38
The ball is delivered by Christopher Burke.33:21
The ball is crossed by Dwight Tiendalli.32:06
Jonjo Shelvey takes the free kick.31:58
Foul by Tom Adeyemi on Jonathan de Guzman, free kick awarded.31:22
Shot by Wilfried Bony went wide of the right-hand upright.30:39
The ball is swung over by Jonathan de Guzman.29:34
Wilfried Bony takes a shot.28:45
Free kick taken by Alejandro Pozuelo.28:34
Callum Reilly gives away a free kick for an unfair challenge on Jonathan de Guzman.27:46
Colin Doyle restarts play with the free kick.27:42
The assistant referee signals for offside against Alejandro Pozuelo.26:28
A cross is delivered by Mitch Hancox.26:10
Clearance by Jordi Amat.26:00
Corner taken by Christopher Burke from the left by-line.25:46
Clearance made by Wilfried Bony.25:06
Corner taken by Christopher Burke.22:10
The ball is delivered by Roland Lamah.21:38
Header at goal by Christopher Burke. A parry by Gerhard Tremmel prevents the goal.21:26
The ball is swung over by Paul Caddis.20:50
Roland Lamah restarts play with the free kick.20:37
Mitch Hancox gives away a free kick for an unfair challenge on Roland Lamah.19:58
Christopher Burke takes the chance to get an effort at goal. Gerhard Tremmel parries the ball away.19:14
Free kick taken by Colin Doyle.19:04
The referee blows for offside against Alejandro Pozuelo.17:33
Alejandro Pozuelo takes a shot and strikes the bar.17:10
Wilfried Bony takes a shot and hits the bar.16:59
Corner from the right by-line taken by Roland Lamah.14:25
Paul Robinson crosses the ball.12:43
Shot by Christopher Burke cleared the crossbar.12:35
Clearance by Wilfried Bony.12:19
Corner from the left by-line taken by Christopher Burke.12:06
Neil Taylor manages to make a clearance.11:47
The ball is swung over by Matt Green.8:58
Paul Caddis restarts play with the free kick.8:47
Paul Caddis fouled by Neil Taylor, the ref awards a free kick.8:18
Wilfried Bony has a direct shot on goal from the free kick. Jonathan Spector gets a block in.8:13
Free kick taken by Wilfried Bony.7:22
Paul Robinson is adjudged to have handled the ball.5:47
Corner from the taken by Jonathan de Guzman.2:27
Leon Britton restarts play with the free kick.2:20
Handball decision goes against Tom Adeyemi.1:44
Wilfried Bony manages to make a clearance.1:31
Corner from the left by-line taken by Christopher Burke.0:00
The ref blows the whistle to begin the match.
Live data and text provided by our data suppliers