It should have been one of this season’s grand occasions. Inter v Napoli as winter turns to spring: a passing-of-the-baton moment with Serie A’s champions-elect hosting the team who shocked the world when they won the Scudetto last year. We wanted fireworks. We got two flamed-out teams, and a game overshadowed by accusations of a player using racist language.

Technically, there were pyrotechnics. Inter were welcomed to San Siro by supporters setting off illuminations and displaying a banner with the words “Fieri di voi” – “Proud of you”. After the disappointment of a midweek Champions League defeat by Atlético Madrid, ultras from the Curva Nord made a deliberate show of gratitude for what has nevertheless been a remarkable year.

Runners-up in Europe’s top club competition last season, Inter did not even mount a serious challenge to Napoli domestically back then. This term, the story has flipped. Failing to reach the last eight of the Champions League is an unambiguously poor result for a team capable of so much more, yet Inter’s disappointment is tempered by knowing they will soon claim their 20th Serie A title, and with it a second gold star to display above their club badge.

A satisfying moment under any circumstances. Made so much sweeter, in this case, by the fact that neighbours Milan are stuck on 19.

Napoli, too, arrived wearing the fresh bruises of a Champions League exit. Theirs was more expected, a two-legged tie against Barcelona always looking like a tall order for a team that have changed managers three times since winning the league under Luciano Spalletti. Yet there were chances, even after they fell behind early in the second leg, and a missed penalty decision could have changed the course of the game at 2-1.

Aurelio De Laurentiis, the Napoli owner, had spoken of his regret at failing to win the Champions League together with Serie A in 2023. He offered his players a €10m bonus to beat Barcelona this time around, knowing that victory would have secured his team a place in next year’s Fifa Club World Cup.

But there is no sum that could turn the clock back 10 months. Napoli were seventh in the table as they headed to San Siro on Sunday. With Roma and Bologna both in brilliant form ahead of them, even qualifying for next season’s Champions League looks like a tall order.

Inter set an aggressive tempo, pressing high and throwing themselves into tackles. They deserved the 1-0 lead that Matteo Darmian earned by converting Alessandro Bastoni’s cross just before the interval. Yet Simone Inzaghi’s team were far from their best. Their advantage owed to furious application, not precision nor clarity of thought.

As legs tired in the second half, Inter got sloppy. Juan Jesus equalised from a corner after being left unmarked at the back post. Before their trip to Atlético, Inter had not conceded a goal inside the final 15 minutes of a match all season. Now they had done it twice in four days.

That was not the most significant part of this story. A few minutes earlier, Jesus had been seen talking to the referee Federico La Penna. From reading lips, it appeared that he was accusing someone of calling him “negro”. An older form of the Italian word for “black”, its translation depends on context but when aimed at another person can be understood as offensive.

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“This is not OK,” Jesus appeared to tell the official. Serie A teams were wearing special badges on their sleeves for this round of games with the message “keep racism out”, part of a league initiative to combat discrimination inside stadiums. Jesus gestured at his after pointing the official in the direction of Francesco Acerbi. Replays showed the pair had exchanged words after a challenge in the Inter penalty area.

No on-pitch consequences were enforced, and Jesus played the incident down at full-time. Asked what had happened, he replied: “What happens on the pitch stays on the pitch. Acerbi apologised and we move forward. When the referee blows his whistle, it ends there … On the pitch, things get said, but he apologised because he knows he went too far. I hope it won’t happen again because he’s an intelligent lad.”

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A magnanimous response, but not everyone will agree with his preference to let the matter lie. Article 28 of the Italian Football Federation’s code of sporting justice sets out strict punishments for “discriminatory conduct” – stipulated to include all “denigration or insult for reasons of race, colour, religion, language, sex, nationality or ethnic origin”. Minimum punishments for this type of offence start with 10-game suspensions.

There has not been any indication yet of whether an official investigation will be opened into the incident.

Even a lengthy ban would not be likely to impact Inter’s march to the Scudetto. Sunday’s game finished 1-1, ending their run of 10 consecutive league wins, but they remain 14 points clear at the top of Serie A. The only real question is whether they will beat the league’s points record – 102, set by Antonio Conte’s Juventus in 2014 – a target which would now require them to win all their remaining nine games.

This weekend’s draw was more valuable to Napoli, who trail fourth-placed Bologna by nine points and fifth-played Roma by six. It is increasingly likely the latter position will suffice for a Champions League spot next season, after another coefficient-boosting round of successes for Italy’s Europa League and Europa Conference League representatives.

“The sums still give us a reason to dream,” said Jesus. “We have all our head-to-heads at home. We need to give everything to try to get into the Champions League and to honour our Scudetto to the end.”