Inter could not have imagined a more satisfying way to win 20th Scudetto

How else could it end but like this: tempers boiling over and the red card being shown to one player after another as Inter sealed their 20th league title with a win over neighbours Milan? Denzel Dumfries and Théo Hernández were first to be sent off after squaring up in midfield at the start of injury time. Milan’s Davide Calabria followed moments later for throwing a forearm into the face of Davide Frattesi at a corner.

And then the final whistle went, transforming a ruck into revelry as the rest of Inter’s players and staff rushed from the dugout to join their colleagues on San Siro’s pitch. They carried giant Scudetto shields displaying the No 20 against the colours of the Italian flag. The two Milan clubs began this season tied on 19 league titles apiece. Now Inter will be the first to affix a second gold star to their club badge.

Related: Internazionale seal historic 20th Serie A title with derby victory over Milan

They could scarcely have imagined a more satisfying way to earn it. Never before had a Serie A champion been crowned in a Milan derby, Inter blowing a previous opportunity when they lost 2-1 to their rivals in May 2008. On Monday, that scoreline was reversed, Francesco Acerbi and Marcus Thuram setting the Nerazzurri on their way before Fikayo Tomori’s 80th-minute header created a fraught finish.

A Milan equaliser would only have delayed the inevitable. Inter’s title has effectively been sewn up ever since the 1-0 win over Juventus at the start of February that dispelled whatever magic had allowed Massimiliano Allegri’s modest team to keep pace. A one-point gap between those clubs became 20 over the next two months.

Milan rose to second but, to borrow the framing that their former manager, Arrigo Sacchi, used after last season’s Champions League semi-final, they were a Fiat Cinquecento chasing a Ferrari. Despite retooling their engine over the summer, selling Sandro Tonali and deploying the profits as part of a more than €100m squad upgrade that included the signings of Christian Pulisic, Ruben Loftus-Cheek and Tijjani Reijnders, they could not get close to Inter.

To watch your rival pull away is painful, but being forced to wait at the finish line and host their celebration is a special kind of nightmare. Milan were the designated home team for Monday’s game at the stadium these clubs share. Before kick-off, Ultras in the Curva Sud adapted an old Banksy mural for their choreography of a maid sweeping Inter under the carpet, accompanied by the words “NOTHING CHANGES”.

They would tell you this second golden star is a hollow achievement, pointing out that Inter’s 20 titles include one awarded retrospectively after Juventus had it stripped as a result of the Calciopoli scandal. A banner unfurled during the game carried the message: “Mathematics is not an opinion. It’s 19 on the pitch.”

Yet the players could not feign such indifference. Yacine Adli responded to his second-half substitution for Milan by furiously kicking every bag, water bottle and box in his sight-line. Tomori sprinted to retrieve the ball after his goal and roared for his team and supporters to keep believing.

Inter had played down the importance of this game before kick-off, with both the manager, Simone Inzaghi, and CEO, Beppe Marotta, insisting that winning here was “not an obsession”. Their words, too, rang false. So many Inter supporters had turned out to encourage them at their training facility on Sunday that Dumfries was forced to abandon his car 1km from the gates and finish his commute in on foot.

There are players in this Inter squad who cheered for the team before they ever had a chance to play for it. Federico Dimarco was going to games at San Siro with his uncle and grandfather from “two or three years old”. Nicolò Barella grew up in Sardinia with Cagliari as his first love but Inter – his father’s team – became a close second as they watched games together on TV.

If they felt this moment more keenly than the rest, then so did Hakan Çalhanoğlu. The Turkey captain joined Inter on a free transfer after his contract with Milan expired in 2021 and was taunted by his former teammates as they won the league title without him the following season.

Revenge is a dish best served cold. On Monday night, Calhanoglu posted to Instagram a mocked-up image of himself sat with the Serie A trophy in front of an angry mob calling him a “traitor” and a “clown”. “Always calm, always patient, always focused and now rewarded,” read the caption.

Inter’s title celebrations flowed from San Siro to Piazza Duomo, fans flooding into the square outside Milan’s cathedral and players arriving later to take up positions on a balcony overlooking them. An official title celebration and open-top bus tour will be planned for the coming days, but there were flags, fireworks, and a tractor here for a preliminary party that lasted past three in the morning.

Beyond even the satisfaction of sealing it with a victory over Milan, this will go down as one of Inter’s very best Scudetto wins. They matched a Serie A record by sealing it with five games to spare. How unlikely that would have sounded 12 months ago. Last April, several newspapers in Italy were confidently reporting that Inzaghi was close to the sack after collecting one point from five Serie A games. Inter’s run to the Champions League final changed the narrative of the season, a reminder of football’s fine margins when you think back on André Onana’s vital saves in the last 16 against Porto.

Inzaghi’s role is fundamental. He had earned himself a reputation as “king of the cups” in Italy, winning the Coppa Italia twice with Inter and once before that at Lazio, as well as raising the Supercoppa five times between the two clubs. Yet this first league title of his managerial career feels like a watershed moment, earning him a more widespread recognition as one of the smartest coaches in Europe.

It bears remembering that Inter sold Romelu Lukaku and Achraf Hakimi in the summer that he joined from Lazio, immediately dismantling key elements of a team that had just won the league under Antonio Conte. Players as talented as Marcelo Brozovic, Ivan Perisic, Edin Dzeko and Lukaku (again, after a brief return) have been allowed to leave since.

That Inter have not only stayed competitive but reclaimed their status as Italy’s top club owes to Inzaghi’s work creating a fluid, thrilling tactical system that allows his players to thrive, as well as some exceptional recruitment by Marotta and his front office team. It felt fitting that Inter’s decisive second goal should be scored by Thuram – the revelation of this season after joining, like Calhanoglu before him, on a free.

Cagliari 2-2 Juventus, Genoa 0-1 Lazio, Verona 1-0 Udinese, Empoli 1-0 Napoli, Monza 1-2 Atalanta, Salernitana 0-2 Fiorentina, Torino 0-0 Frosinone, Sassuolo 0-3 Lecce, Milan 1-2 Inter, Roma 1-3 Bologna

There is optimism that this project can continue to go from strength to strength, amid reports this week that the club president, Steven Zhang, is close to negotiating a new loan that would allow him to refinance debts of close to $300m that could otherwise force him to sell the club.

Those, though, are thoughts for another day. For Inter, this is a moment simply to revel in a second golden star, and total domination of a rival. They have beaten Milan in six consecutive derbies – another record, and a major factor in the declining popularity of Inzaghi’s opposite number, Stefano Pioli, with his own club’s supporters.

The red-and-black half of Milan is ready for a change. It might take more than a new person behind the wheel, though, to chase down this runaway Inter.