Javier Zanetti could have taken the day off. Nobody at Inter would have objected if their captain, 39 years old and four days removed from the 1,100th game of his professional career, had skipped training last Thursday in order to fulfil a great personal dream. He had been invited that afternoon for an audience with Pope Francis at the Vatican.

A devout Catholic and proud Argentinian, Zanetti was thrilled by this opportunity; Pope Francis was the first man from Zanetti's home country to have been elected as head of the church. But the appointment clashed with a team training session. Instead of asking to be excused, Zanetti requested to have an individual practice first thing in the morning, early enough that he could still get to the airport in time.

Zanetti, after all, has never been afraid of an early start. Informed by Independiente's coaches at the age of 15 that he was too small to make it as a professional footballer, Zanetti found a job delivering milk to local supermarkets with his cousin Carlo instead. The working day began at 4am, and yet, as Zanetti grew taller and rediscovered his footballing confidence, he soon found the stamina to go and train with a new club, Talleres, every evening as well.

This was a formative period. Physically Zanetti grew stronger as he helped his father, a bricklayer, to build walls in his spare time. He grew up in other ways too. For a long time Talleres were unable to offer Zanetti a wage, meaning he had no choice but to carry on delivering milk (as well as taking on other jobs) to support himself and help out his family.

Maturity and work ethic, however, were not the qualities that persuaded Massimo Moratti to make Zanetti his first signing for Inter. Shortly after Moratti completed his purchase of the club in 1995, he was passed some videotapes from that year's Pan American Games. The owner was mesmerised by the dribbling skills of a young Argentinian named Zanetti, who weaved through opponents as though the ball was part of his anatomy.

Zanetti's new Inter team-mates would be similarly impressed. "At his very first training session, we were doing a possession exercise," recalled his then captain Giuseppe Bergomi. "He never lost the ball, it was always glued to his foot. That day I knew he was going to make history."

Even Bergomi, though, could not have predicted quite what was coming next. Eighteen years on, Zanetti holds the all-time records for most appearances for Inter (847) and the Argentinian national team (145). Only Paolo Maldini has played more games (647) than Zanetti (603) in Serie A. The Argentinian has won the Scudetto five times, the Coppa Italia four times and the Uefa Cup once. As captain he led Inter to a treble of league, cup and Champions League success in 2010.

Nor has Zanetti allowed such achievements to go to his head. He retains not only the same haircut but also the same modesty and social conscience with which he arrived. When he first reached Milan, Zanetti immediately volunteered to help out with a charity set up by Bergomi to aid disadvantaged children. In 2001 Zanetti, together with his wife Paula, launched the Fundación Pupi, a non-profit organisation with similar ambitions back in Argentina.

Charity work was among the topics of conversation when Zanetti finally did meet with Pope Francis last week. "It was an emotional experience because from the moment he was elected, my greatest desire has been to meet him," said the Inter player. "I found him to be a simple person, with an enormous heart, who will devote his energies to helping the faithful."

Asked by reporters if he had won the Pope round to supporting Inter, Zanetti delivered a perfectly diplomatic riposte: "No, the Pope cheers only for a better world."

On Sunday Zanetti led Inter out on to the field in Palermo wearing a special commemorative captain's armband – one that showed the Papal coat of arms as well as the national flags of Argentina and the Vatican City. Perhaps, deep down, he was hoping for a little divine assistance. Inter had lost four of their previous six league games, putting their European aspirations in jeopardy.

This armband, though, was not destined to be associated with happy memories. In fact, it may be the last one Zanetti ever wears. In the 17th minute of the game, with his team already trailing 1-0, Zanetti hobbled off the pitch gesturing frantically to be substituted. Then he collapsed, screaming, to the floor. He had ruptured his left achilles tendon.

Swiftly he was removed on a stretcher and whisked away to hospital. Polite to a fault, however, Zanetti still found time to speak briefly with journalists before being transported out of the stadium. "I felt a pulling, an extremely serious pain," he said. "But I will overcome this."

He reiterated that same message later in the evening, once the diagnosis had been confirmed. "My career does not finish here," he said. "After travelling so many kilometres, I just needed to change my tyres. I want to come back even stronger than before. My only sadness is not being able to help my team-mates qualify for the Europa League, but I have faith that they can do it."

It was an optimistic message from an optimistic man, one who has been defying received wisdom on the human aging process for many years. Zanetti has started 33 of Inter's 34 league games this season. He has featured in more than 90% of Inter's fixtures across all competitions since 1995.

But the stark reality is that a torn achilles will require a minimum of six months' rehabilitation and likely more than that. Zanetti turns 40 in August, and even he cannot go on forever.

The reaction from around the country showed how greatly Zanetti is respected. From Antonio Conte to Mario Balotelli, coaches and players lined up to wish him a speedy recovery. One or two tasteless chants were heard during Milan's win over Catania, with one section of supporters inviting Zanetti to "jump with us", but the Inter captain shrugged them off, saying: "These things happen".

Without him, Inter lost 1-0 – finding no response to Josip Ilicic's 10th-minute opener, elegantly converted after a calamitous non-clearance from Matías Silvestre gifted possession to Fabrizio Miccoli inside the area. This was Inter's 13th league defeat of the season, and only Palermo's sixth win. It was, indeed, a result with significant ramifications at the bottom of the table, moving Palermo above Siena and into 17th.

Inter, meanwhile, not only slid to seventh but lost yet another player – Silvestre exiting with a suspected hamstring strain midway through the second-half. An incredible 15 members of their first-team squad are presently out of action due to injury. Zanetti, though, will be missed more than most.

Talking points

• Juventus will have to wait another week to lift the Scudetto, Napoli's 3-0 victory away to Pescara preventing the Bianconeri from sealing the title at the home of their city rivals Torino despite a 2-0 victory in the Derby della Mole. Italian football was confronted with yet more unedifying scenes in the hours leading up to kick-off in Turin, as a window of Juve's team bus was smashed by a rock and five supporters were arrested for brawling in the streets outside the Stadio Olimpico.

• Torino's Riccardo Meggiorini defended himself on Sunday evening against claims he had racially abused Paul Pogba during the game. In a turn of phrase that echoed some of Juve's own fans (see last week's Talking points), Meggiorini denied racism but defended his right to abuse Pogba generally. "There was an insult, but it wasn't racist," said Meggiorini. "It was a normal insult, the sort that happens all the time on the field. Pogba shouldn't start crying whenever somebody says anything to him."

• Revelation of the week comes from Andrea Pirlo's new autobiography Penso quindi gioco – I think therefore I play – in which he comes clean about what appears to be a fairly serious video game habit. I've not yet got my hands on a copy, so this quote comes via the always reliable James Horncastle: "After the wheel, the greatest invention in history is the PlayStation."

• Third-placed Milan maintained their one-point advantage over Fiorentina, beating Catania 4-2 in a topsy-turvy game at San Siro. Despite dominating the game, the Rossoneri twice fell behind and were only rescued by two goals in three minutes from the substitute Giampaolo Pazzini. For all the focus on Milan's mohawked trio of Mario Balotelli, Stephan El Shaarawy and M'Baye Niang, Pazzini's impact on this season has been about as significant as any of them. He has now scored 15 goals in 26 league appearances – only 15 of which he actually started.

• Massimiliano Allegri received the backing of Milan's supporters in the Curva Sud, where a large banner was hung with the message: "More respect for our boss Allegri". It had been reported in Sunday's Gazzetta Sportiva that Silvio Berlusconi was lining up Clarence Seedorf to replace the manager.

• Fiorentina finished the weekend behind Milan, but theirs was nevertheless an impressive performance, beating Sampdoria 3-0 in Genoa. Much as he denied it afterwards, you have to believe that Adem Ljajic especially enjoyed his goal against a team managed by Delio Rossi – a manager who infamously threw punches at him in the Fiorentina dugout last May.

• It was a nightmare weekend for Siena at the other end of the table, as they were crushed 4-0 by Roma (and some very nice goals there were, too), while Palermo and Genoa both won. It was enough to drag Siena back into the relegation zone, and things won't get any easier from here. Next week they travel to Catania to face a team that has lost only three times at home all season. Siena's remaining three opponents after that are Fiorentina, Napoli and Milan.

Results: Atalanta 1-1 Bologna, Cagliari 0-1 Udinese, Chievo 0-1 Genoa, Milan 4-2 Catania, Palermo 1-0 Inter, Parma 0-0 Lazio, Pescara 0-3 Napoli, Roma 4-0 Siena, Sampdoria 0-3 Fiorentina, Torino 0-2 Juventus.

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