Marcus Rashford had a hand in all three goals as Manchester United beat Colchester 3-0 to reach the Carabao Cup semi-finals.
Rashford took advantage of a rare Colchester attack leaving them exposed at the back to beat Dean Gerken after a solo run, and five minutes later had a hand in their second as Mason Greenwood's cross was turned past Gerken by Ryan Jackson under pressure from the Manchester United forward.
- Manchester Derby in Carabao semis
- Carabao Cup results | Fixtures
- How the teams lined up
- Find out more about Sky Sports
He then set up the third goal to kill the game as a contest soon after when turning Juan Mata's cross back across goal to provide Anthony Martial a simple finish.
Manchester United: Romero (6), Young (7), Tuanzebe (6), Maguire (7), Shaw (7), Matic (6), Pereira (6), Greenwood (7), Mata (7), Rashford (8), Martial (7).
Subs: Williams (6), Lingard (5), Garner (6).
Colchester: Gerken (7), Jackson (6), Bramall (6), Lapslie (6), Prosser (6), Pell (7), Norris (6), Comley (5), Harriott (7), Eastman (6), Nouble (5).
Subs: Stevenson (6), Poku (6).
Man of the match: Marcus Rashford
The hosts had struggled to turn their first-half dominance into clear opportunities against a side three divisions below them, but once they found the breakthrough, they added the second and third goals with relative ease to secure a spot in the last four against arch-rivals Manchester City.
How Man Utd laboured into semi-finals
Manchester United arrived at Old Trafford acutely aware only a sizeable win would satisfy expectations against a side 61 places below them in the football pyramid, and named a strong team against opponents unbeaten in League Two since mid-October.
Their domination was constant and their residence inside the Colchester half almost endless, but their final ball was very poor in a first half in which Gerken had little of note to worry him.
Colchester have prided themselves on a strong defence this season but Manchester United should still have tested them far more before the break, and only Rashford's sliced miscue from a floated ball into the box looked like it could have threatened a breakthrough.
Manchester United changed seven players from the draw with Everton on Sunday, but did keep Marcus Rashford, Anthony Martial, Harry Maguire and Luke Shaw in from that game.
Colchester made two changes from their weekend draw with Scunthorpe, bringing in Tom Lapslie, who scored the winning penalty in the shoot-out win over Tottenham in round three, and Callum Harriott.
The anxiety levels were rising around Old Trafford, in the knowledge Colchester had dispatched two other Premier League teams on penalties after goalless draws earlier in the competition, but six minutes into the second half they were immediately relaxed.
Colchester committed men upfield in a rare attack from which right-back Jackson's cross was cut out, and on the break Manchester United took full advantage of the visitors' positioning, with Rashford cutting inside off the left before drifting past two challenges and firing beyond Gerken.
Two goals in the next 10 minutes killed any remote hope Colchester had of keeping their dreams of another Premier League scalp alive, and they gave the hosts a helping hand with their second when Greenwood's awkward cross from the right was turned in by Jackson, who could not move his leg out of the ball's path in time with Rashford lurking.
Manchester United saved the best for last to make it 3-0, with Martial left with a simple finish to secure their progression to the semi-finals when Rashford ended a long spell of possession by side-footing Mata's cross back across the six-yard box for him to slot home.
The hosts could have added to their lead late on when Harry Maguire was denied a fourth from a corner by a flying Gerken save, but they escaped unscathed to reach the last four, moving them a step closer to lifting the League Cup trophy for the first time since 2017.
What the managers said...
Ole Gunnar Solskjaer: "I thought we played well first half, but we were wasteful. I think we played miles better in the first half than the second half, but we scored and in games like this you need a first goal to settle any doubt and then spaces will come, and it'll flow more.
"But I think we did okay, actually. They kept a clean sheet against Palace and Tottenham, and we knew they'd be
hard to break down.
"In the end, the first time they really went for it, had a chance, counter-attack and of course that settled everything."
On Manchester United's semi-final draw with Manchester City: "Of course, we do really respect them and, as I said after the game at the derby last time, it's in my opinion the best team in England.
"They can out-football you, so we need to get our game heads on and be ready for them again.
"But we've shown them that we can cause them problems, so I think they'll be two fantastic games."
Man of the match - Marcus Rashford
Given the number of chances he had, we should have been talking about a Rashford hat-trick, but he did prove the difference in dispatching an awkward Colchester with his second-half performance.
His first goal showcased his improving composure while his movement and persistence played their part as the hosts added their second and third goals. He had seven shots, three more than anyone else, and took on opposition players more times (11) than anyone else.
- Manchester United have progressed from all 11 of their League Cup ties against fourth-tier opponents.
- Colchester conceded three goals in a match for the first time in 38 matches, since losing 3-0 to Exeter City in a League Two match in March.
- Marcus Rashford has scored 14 goals in all competitions for Manchester United this season, his best return in a single campaign for the club.
- Manchester United have reached their 15th League Cup semi-final - only Liverpool have reached more in the competition's history (17).
Live Renault Super Sunday
Manchester United travel to Watford at 2pm on Super Sunday - live on Sky Sports Premier League from 1pm - while Colchester host Carlisle in League Two on Saturday at 3pm.