Match ends, Swansea City 0, Manchester United 2.
Carabao Cup holders Manchester United reached the quarter-finals with a comfortable victory at Swansea City.
A much-changed United side controlled the tie and led at half-time as Marcus Rashford's deft back-heel allowed Jesse Lingard to score with a neat low finish.
The visitors doubled their lead in fine fashion after an hour, with a sweeping team move teeing up Lingard to head in his second.
Swansea, who had made eight changes themselves, offered precious little in attack as they succumbed to a fifth defeat from six home games this season.
United spurred on by Mourinho's words
Although United manager Jose Mourinho has won the League Cup four times during his career, he had suggested after the third-round win over Burton Albion that teams in Europe could benefit by not playing in this competition.
It was therefore no surprise that United made seven changes for their trip to south Wales, having suffered their first Premier League defeat of the season at Huddersfield on Saturday, after which Mourinho criticised their "poor attitude".
The barb seemed to have the desired effect, with three of the players involved at Huddersfield - Lingard, Rashford and Anthony Martial - setting the pace for a vibrant United start in Swansea.
The first two combined beautifully for the opening goal, as Rashford artfully flicked an Ander Herrera pass into the path of Lingard, who guided his low finish into the bottom corner.
United's second goal was equally impressive. Axel Tuanzebe started the move with a marauding run from defence and spread the ball to Matteo Darmian, whose pinpoint cross was headed in by Lingard.
Mourinho said that his side's application and concentration, like the result, were much improved from the weekend defeat at the John Smith's Stadium.
"Our attitude was very good. I'm really happy," he said.
"We were solid, we were comfortable, we were in control."
The victory marked Mourinho's 400th game in English football, accumulated over two separate spells at Chelsea as well as his time at Old Trafford.
"Of course I still get the same thrill from it, but 2004 was a long time ago," said the Portuguese.
"I am more mature and have a different way to react to things. I'm the same. I want to win and I hate losing."
Swansea's struggles continue
Swansea's indifferent start to the season had seen them lose four of their five home league games, prompting head coach Paul Clement to make eight changes to the team beaten by Leicester on Saturday.
The squad rotation was meant to give some of his players a rest, but Clement's worst fears became reality at the end of the first half as Martin Olsson - the club's only specialist left-back - was forced off the field with a hamstring injury.
His withdrawal compounded a forgettable evening for the hosts as they barely forced their opponents out of first gear.
Among Swansea's new faces was 21-year-old striker Oli McBurnie, making his first start of the season after his proposed loan move to Championship club Barnsley had fallen through on transfer deadline day because the deal's paperwork had not been completed correctly.
However, his isolation up front was symptomatic of a Swansea display almost entirely devoid of attacking threat.
Swansea manager Paul Clement: "Always disappointed when you lose a game. We actually played better than we have been recently but Manchester United deserved to win the game, no question about that.
"We created a decent amount of chances, maybe nothing clear-cut until the last moment when [Sergio] Romero made that save from a set-play.
"They deserved the victory, they had the extra bit of quality and from our point of view, we just have to believe a good result and good performance is around the corner.
"We have to show determination to get through this difficult time that we're having."
Man of the match - Jesse Lingard
- 22RangelBooked at 38mins
- 5van der Hoorn
- 16OlssonSubstituted forNaughtonat 39'minutes
- 4Ki Sung-yuengBooked at 70mins
- 51MesaSubstituted forFerat 67'minutes
- 17ClucasBooked at 56mins
- 18J Ayew
- 62McBurnieSubstituted forAbrahamat 72'minutes
- 38TuanzebeBooked at 75mins
- 21HerreraSubstituted forMaticat 67'minutes
- 17BlindBooked at 79mins
- 19RashfordSubstituted forLukakuat 67'minutes
- 11MartialSubstituted forShawat 87'minutes
- 40Castro Pereira
- Robert Madley
- Shots on Target
Second Half ends, Swansea City 0, Manchester United 2.
Corner, Swansea City. Conceded by Sergio Romero.
Attempt saved. Leroy Fer (Swansea City) left footed shot from the right side of the six yard box is saved in the centre of the goal. Assisted by Mike van der Hoorn.
Attempt missed. Mike van der Hoorn (Swansea City) header from the centre of the box misses to the right. Assisted by Ki Sung-yueng with a cross following a corner.
Corner, Swansea City. Conceded by Scott McTominay.
Attempt blocked. Kyle Naughton (Swansea City) right footed shot from outside the box is blocked. Assisted by Leroy Fer.
Jesse Lingard (Manchester United) wins a free kick on the left wing.
Foul by Leroy Fer (Swansea City).
Attempt blocked. Nemanja Matic (Manchester United) left footed shot from the left side of the box is blocked. Assisted by Jesse Lingard with a cross.
Substitution, Manchester United. Luke Shaw replaces Anthony Martial.
Corner, Manchester United. Conceded by Alfie Mawson.
Matteo Darmian (Manchester United) wins a free kick in the defensive half.
Foul by Tammy Abraham (Swansea City).
Attempt blocked. Jordan Ayew (Swansea City) right footed shot from outside the box is blocked. Assisted by Sam Clucas.
Foul by Anthony Martial (Manchester United).
Mike van der Hoorn (Swansea City) wins a free kick in the defensive half.
Attempt saved. Jesse Lingard (Manchester United) left footed shot from outside the box is saved in the centre of the goal. Assisted by Matteo Darmian.
Offside, Swansea City. Tammy Abraham tries a through ball, but Wayne Routledge is caught offside.
Victor Lindelöf (Manchester United) wins a free kick in the defensive half.