Match ends, Manchester City 4, Port Vale 1.
Phil Foden made one goal and scored another as holders Manchester City saw off a spirited Port Vale side to book their place in the fourth round of the FA Cup.
City, who won all four available domestic trophies last season, had to work hard to break down their League Two opponents, but eventually ran out comfortable winners.
Oleksandr Zinchenko put Pep Guardiola's side ahead with a rasping shot from distance that Vale captain Leon Legge could only help into his own net.
But City failed to turn their superior possession into further goals and were surprisingly pegged back by a superb Tom Pope header from a pinpoint David Amoo cross.
That sparked wild celebrations from more than 8,000 Vale fans who packed the top tiers of the south stand at Etihad Stadium, but their side were level for only seven minutes.
City kept pouring forward and Foden set up Sergio Aguero to fire home at the near post, with Legge again getting the final touch.
That goal was checked by the video assistant referee before being awarded; when City scored their third goal just before the hour mark, it was initially ruled out and needed VAR intervention before being given.
Taylor Harwood-Bellis was flagged offside when it appeared John Stones had put the ball into the net but replays showed the 17-year-old had got the final touch, and was actually onside too.
On a good day for City's academy, two more graduates combined for City's fourth goal, with Foden running into the box to bury Angelino's shot past Scott Brown.
Pope makes his point with a goal
The derogatory comments Pope made about Stones on social media last summer, when he called him 'a target man's dream', added extra spice to this tie, especially when both men were named in their respective starting line-ups.
But Pope, 34, had given some more insight into his thinking this week when he talked about how he likes to prey on the weakest link in any defence, so it was no surprise to see him lurk near Harwood-Bellis instead.
That was how he found space to convert Amoo's cross at the near post, darting away from his teenage marker at the last second.
Stones, back in the City side after a month out with his latest injury, got the better of the veteran forward whenever their paths crossed directly.
But it was still fitting that he and Harwood-Bellis combined to score City's third goal, and ensure any personal battle with Pope finished all-square.
Man of the match: Phil Foden (Manchester City)
'Why this competition is so special' - what they said
Manchester City manager Pep Guardiola told BBC Sport: "When Port Vale get contact with Tom Pope and run, they are a danger. In the second half, we created a lot of chances so we are into the next round."
On Taylor Harwood-Bellis' performance: "He is growing every day and he is a player with a lot of quality. He played in the Carabao Cup and did well and he is a guy who is always so focused.
"This is the oldest cup competition in this country, so of course these kind of games you take seriously and you do what you have to do. We will be in the draw but it is still a long way to reach the final."
On inviting Port Vale players into the home dressing room: "It is a pleasure when these teams can be alongside our players and why this country and this competition is so special."
Port Vale manager John Askey told BBC Sport: "I thought they [Vale's players] were fantastic. I'm really proud of them to come here and hold them for so long. Going into half-time you have to pinch yourself that it's 1-1. We knew it was going to be tough and before the game I was worried that teams have come here and been annihilated but I'm sure the fans are proud of the team.
"We rode our luck a little bit at times. When that goal [Tom Pope] went in, you start to dream a little bit. I was disappointed in the three goals we conceded before the fourth because they were avoidable and it was somebody's heel that kept them onside.
"Our supporters never stopped throughout the game. I'm so proud, and to see so many people come from Stoke-on-Trent cheering us on, I could not have asked for much more. I have just been in his [Pep Guardiola's] office and he poured me a glass of red wine. We spoke about football and it was nice to have a chat."
City continue their defence of the Carabao Cup with the first leg of their semi-final against Manchester United at Old Trafford on Tuesday (20:00 GMT).
Vale are in action only a few miles down the road on the same night, taking on Salford City in the EFL Trophy (19:45 GMT).
- 8GündoganSubstituted forDoyleat 77'minutes
- 20Bernardo SilvaSubstituted forMahrezat 77'minutes
- 9Gabriel Jesus
- 20BurgessSubstituted forConlonat 61'minutes
- 16TaylorSubstituted forAtkinsonat 61'minutes
- 9PopeSubstituted forCullenat 79'minutes
- Lee Mason
- Shots on Target
Second Half ends, Manchester City 4, Port Vale 1.
Corner, Manchester City. Conceded by Leon Legge.
Attempt blocked. Phil Foden (Manchester City) left footed shot from the centre of the box is blocked. Assisted by Angeliño.
Corner, Manchester City. Conceded by Scott Brown.
Attempt saved. Riyad Mahrez (Manchester City) right footed shot from the right side of the box is saved in the centre of the goal. Assisted by Sergio Agüero.
Attempt missed. Sergio Agüero (Manchester City) right footed shot from the centre of the box is too high.
Riyad Mahrez (Manchester City) wins a free kick in the defensive half.
Foul by Cristian Montaño (Port Vale).
Corner, Manchester City. Conceded by Mark Cullen.
Corner, Manchester City. Conceded by Nathan Smith.
Foul by David Silva (Manchester City).
James Gibbons (Port Vale) wins a free kick in the defensive half.
Substitution, Port Vale. Mark Cullen replaces Tom Pope.
Substitution, Manchester City. Riyad Mahrez replaces Bernardo Silva.
Substitution, Manchester City. Tommy Doyle replaces Ilkay Gündogan.
Goal! Manchester City 4, Port Vale 1. Phil Foden (Manchester City) left footed shot from the centre of the box to the bottom left corner. Assisted by Angeliño with a cross.
Attempt blocked. Ilkay Gündogan (Manchester City) right footed shot from outside the box is blocked. Assisted by Phil Foden.
Attempt missed. David Silva (Manchester City) left footed shot from the left side of the box misses to the right. Assisted by Angeliño.
Sergio Agüero (Manchester City) wins a free kick in the attacking half.