A supermarket plastic bag. Not a diamond-encrusted designer holdall. All he was carrying was a plastic bag containing his boots and ID. "Excuse me," he said to the fans, journalists and autograph hunters milling outside FC Internazionale Milano's training ground, waiting for new signings. Nobody recognised Javier Zanetti until it was too late. "When I stepped on to the balcony, the fans couldn't believe it. I'd just walked through them and they had no idea who I was. Not even the gateman."

Now, 17 years and 16 trophies later, Zanetti still laughs about his first day at Inter. And he still has the same attitude. If it were up to him, he would still carry his boots in a plastic bag. The Argentinian, 39 next month, is arguably the humblest football legend of the past two decades.

"When I signed my contract, they made me choose a car. I picked a BMW, but the day before my first training session I felt strange. So I phoned [Inter captain] Giuseppe Bergomi and asked if it was OK that I show up in a BMW. I didn't want to send the wrong message to my new team-mates. But when I arrived, I realised my car was the ugliest in the whole car park! And I felt much better."

Zanetti also remembers how difficult it was to talk to his then girlfriend, now wife, Paula, when he first moved to Italy. The public telephone, two blocks away from his house in Como, virtually became his personal domain. "I would buy a cheap calling card and spend hours in that cabin. In winter it was freezing and my hands would end up shaking. But it was worth it. The problem was for the other people waiting to use the payphone. Imagine the things they'd have been saying! Then, fortunately, I bought a fax machine."

He hasn't changed much: same haircut, same baby face as on that day in 1995 when he wore a suit for the first time and was introduced to the Inter supporters. Few would have thought then that he would become the club icon and serial record breaker he is today.

Every time he plays, every moment he walks onto the pitch, Zanetti sets a new milestone. Matching his achievements will be almost impossible. He has played more than 1,000 professional games. He is the most-capped player for Argentina and leads every chart at Inter, including most seasons as captain, most Serie A outings and most appearances overall.

That last one was the latest record he snatched from Bergomi, attained last September against PFC CSKA Moskva. Zanetti's contract expires next year, when he will be almost 40. Yet Bergomi, nicknamed 'Lo zio' (Uncle) doubts his successor will retire soon. "One day I joked about him being able to play until he is 50," Bergomi said. "Now I seriously believe he can play until he's 45. His fitness is intact. Like with Paolo Maldini, it will be for him to decide when and why to quit football. He is superhuman."

The day he broke Bergomi's Serie A appearance record, a banner in the stands read: "Pupi [Zanetti's nickname], you've surpassed the Uncle and still look like his nephew." His former team-mate Gianluca Pagliuca congratulated him, albeit with a hint of fear: "I hope you play just two more seasons, otherwise you'll beat my record of 592 games." Zanetti has played 570 to date. Maldini racked up 647 matches in 25 years.

"All the records are special, but I have two favourites," says Zanetti. "One is Argentina's most capped player – considering how difficult it is to play in a country like mine, where great new players are emerging all the time. The other is being Inter captain for 12 years and having the record number of appearances, especially as a foreigner, which really stands out."

Is there a secret to his longevity? "I don't mess around when it comes to fitness. Also, the harmony you find at home, with a beautiful family, helps you think just about football. My secret is to train as intensively as I can, if possible, with the same intensity you experience in a real match."

Obsessed with his daily routine, Zanetti turned up at Argentina's training camp even on the morning of his wedding. It is not uncommon to find him at Inter's training ground during his holidays either. He just does not want to stop. "My team-mates at Inter mock me when we are training. 'Stop running, let us win for a change,' they joke. But as long as my body responds, I will keep playing."

This is an edited version of a piece in Champions #54. To read the full interview, subscribe here.