The most startling cheer of a boisterous, balmy night in Turin came 10 minutes after the final whistle as the last of the victorious Juventus players left the pitch. Gianluigi Buffon turned and ran towards the Curva Sud, still thronging with flags, and drew a huge, ragged shout of joy from the Juve fans as he leapt about pumping his fists.

Buffon will now play his third Champions League final after an energetic but always controlled 2-1 defeat of Monaco, and a 4-1 win overall for a Juventus team that won this semi-final with something to spare, like a cagey old champion boxer keeping a slick young challenger at arm’s length.

On this form Italy’s grand old man of the lime green jersey looks pretty well placed finally to win one. Still to be really stretched in the knockout stages, Juventus will provide a mighty obstacle for whichever Madrid team joins them in the final.

Either way the great black and white blockade will roll on to Cardiff, though not without a minor scratch on the way. Juventus were at least made to work a little by Monaco in Turin, conceding a first goal in 689 minutes in this competition as Kylian Mbappé slipped the ball past Buffon with the game already buried.

Two goals down after the first leg, Leonardo Jardim’s Monaco were always up against it here. Juventus had won all previous 11 knockout ties against French opponents. Monaco had never won in Italy. In addition Juve’s run to this stage had been based around that famous impregnability, not around some celebrity front three but with its coolest, hippest stars in defence, great beaky broken noses splashed across a million keyboard-fanboy bedroom walls.

Here Leonardo Bonucci, Giorgio Chiellini and Andrea Barzagli – combined age 98 – lined up once again in a back three, with Dani Alves and Alex Sandro the wing-backs pushed wide and high. Monaco had got to this stage playing without fear and they began in the same style, Buffon flapping at one early cross after a corner won by Benjamin Mendy, a late replacement after Nabil Dirar was injured in the warm-up.

Mendy was at the Juventus throat straight away, steamrollering up the left, from where Monaco almost penetrated the home goal with five minutes gone, Mbappé hitting the post with a cut-back from a fine angle.

Juve were a little rattled. Sami Khedira limped off, replaced by Claudio Marchisio, as Mendy and Mbappé continued to carry the fight, Mbappé battling with Chiellini with his back to goal and showing great composure and skill on the ball when he managed to turn.

Steadily Juve began to make headway on their right, where Alves linked nicely with Gonzalo Higuaín. Some strikers have a yard of space in their head. Matched against Monaco’s super-svelte athletes, Higuaín looked at times as if he keeps one up his jumper. But his movement is still full of menace and three times he scampered in on goal. A hopeless dinked finish drifted wide. A low poke drew a fine low save from Subasic.

Mario Mandzukic puts Juventus ahead on the night against Monaco. Photograph: Andrea Di Marco/EPA

The goal was coming, although it arrived from a break the full length of the pitch. Buffon threw the ball netball style to Alex Sandro, who zoomed off into the open grass. The ball found its way out to Alves on the right. His deep cross was headed powerfully down by Mario Mandzukic.

Subasic saved, Mandzukic smashed the rebound high into the net and the Curva Sud dissolved into a huge seething bank of gleeful noise.

Juve were surging away, looking like a team that have arrived at the season’s final breaths in good health, gears clunking, moving parts grooved and settled. Monaco almost snatched one back, Mbappé denied a tap-in after brilliant work from Mendy by Chiellini’s last ditch interception.

But almost immediately it was 2-0, Alves smashing a volley past Subasic from outside the right side of the area after the ball had looped back to him. It was an extraordinary finish, and at a killer time too just before the break. Monaco trooped off looking a little numb, reeled in by more seasoned opponents, the tie seized with ruthless, controlled brilliance.

Still they kept coming. Buffon produced a wonderful reflex save at his near post and with 68 minutes gone Monaco achieved something of genuine note by finally putting a goal past this Juventus defence, the first from open play in the 12th game of this Champions League season.

Mbappé scored it, darting in to turn in João Moutinho’s cut-back and becoming in the process the youngest player to score in a semi-final in this format. There was a minor rumble in the Juve penalty area shortly after Kamil Glik had clearly stamped on Higuaín at the other end as he tumbled in front of him.

From there the game became a celebratory final trot, the stadium rising to this settled, powerful team full of craft, who will now look to Cardiff and the chance to become champions of Europe again, 21 years and four losing finals since the defeat of Ajax on penalties in Rome.