Erling Haaland took us his goal tally to 15 in 17 appearances this season with a first-half penalty and stunning second shortly after the restart.
His strikes were sandwiched by a wonderful individual goal from Phil Foden as we went in two goals ahead at half-time.
Victory means we become just the fourth holders of the trophy to win their first four games the following season as we reached the knockout stages for an 11th consecutive campaign.
Pep Guardiola initially made six changes to the side that beat Bournemouth at the weekend but was forced into a late alteration just before kick-off with Manuel Akanji unavailable; Kyle Walker taking his spot as well as the captain’s armband.
The City boss could have moved Rico Lewis back but chose to keep him in the midfield role where he impressed with his energy and intelligence in the victory at RB Leipzig on matchday two.
And almost a year to the day since he burst onto the European scene with a goal in an Etihad win over Sevilla, the 18-year-old was close to putting us ahead inside six minutes after Jack Grealish teed him up, only for Loris Benito to scramble Lewis’s shot off the line with the goalkeeper beaten.
Young Boys number one Anthony Racioppi, who was in sparkling form two weeks ago for our 3-1 win in Switzerland, was into the action soon enough, scooping away Walker’s free-kick and reacting quickly to block Foden’s close-range follow-up.
But he was beaten midway through the first half from the penalty spot; Haaland sending him the wrong way from 12 yards after Matheus Nunes was caught by a clumsy challenge from Sandro Lauper.
With 75% of possession, City went close again through Haaland’s far post before finally doubling our lead on the stroke of half-time with a dazzling individual effort from Foden.
Coming off the right wing, an exquisite touch took him away from the strong challenge of Ulisses Garcia as he cut inside before sliding a precision finish beyond Racioppi from a tight angle.
Haaland provided his own moment of brilliance shortly after the restart, drifting across the box before unleasing a thumping 20-yard strike that gave Racioppi no chance.
While it was another busy night for the visiting keeper, City stopped Young Boys having a single shot on or off target with Ederson at least entertained by the lively away fans that had travelled from Switzerland and were behind his goal for the second half.
Trailing 3-0, Young Boys’ hopes of rescuing the game looked remote and it became virtually mission impossible moments after Haaland’s second when Lauper was sent off.
Lewis showed he wouldn’t be bullied either when Young Boys skipper Mohamed Ali Camara, towering above him, gave the City player a shove off the ball and was met by an angry rebuke.
City continued to push to to add our lead with Kalvin Phillips, Mateo Kovacic and Nunes all firing just off target while Grealish and Jeremy Doku were denied by Racioppi but the result was long since secured.
YOUNG BOYS XI: Racioppi, Garcia (Persson 78), Benito, Amendo, Camara (C), Janko (Blum 66), Lauper, Niasse, Ugrinic (Males 88), Itten (Chaiwa 66), Elia (Ganvoula 78).
Subs: Von Ballmoos, Marzino, Colley, Lustenberger, Nsame, Monteiro, Rrudhani.
MAN OF THE MATCH
City star Foden continues to shine in the inside right position that has become a familiar role for him this season.
The Academy product has been hugely effective throughout his Etihad career mainly working off the left flank.
But he’s swapped sides this season and continues to make an impact, taking his tally to three goals in three games after strikes against Manchester United and as a substitute against Bournemouth.
PEP GUARDIOLA REACTION
“Sometimes you have to fight against the tendency of what people think about us and what is going to happen. The important thing is it happened.
“People say we are going to qualify for sure, okay we have qualified but the job is not done because we have to finish first. It’s better to have the second leg in the last 16 at home because at home we feel confident.
“Still we have a job to do but the first step to qualify is done. I’m really impressed.
“We scored two fantastic goals, second and third were amazing goals. We’ve played good games.
“Still after what we have done, the uncomfortable things that are always required in a football, still we are able to do amazingly.”
JACK GREALISH REACTION
“We have a brilliant team, on the pitch and also off the pitch, we have a team that is so close. We love being with each other and we love playing with each other and that shows on the pitch.
“Before the game, the manager said to me that when we have the ball, we normally go from me to Kovacic to Rodri.
“But he said when they have the five at the back, hit it to the other side straight away. Instead of going to each player because that takes longer.
“I got it to Phil straight away to get at the defender one on one and that’s what he did.”
WHAT IT MEANS
City have qualified the Round of 16 with a game to spare after winning our first four matches in Group G.
RB Leipzig have also secured a place in the knockout stages and could still finish top of the group above us to claim the seeded place in the draw.
We head to London next aiming to go in the international break top of the Premier League.
City face Chelsea at Stamford Bridge on Sunday 12 November at 16:30 (UK) with Mauricio Pochettino’s side winning away to previously unbeaten Tottenham on Monday night.
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