Old friends Pirlo and Gattuso meet on the touchline for first time

It was one of football's most successful midfield partnerships: on the one hand, the snarling, combative Gennaro Gattuso, and on the other, the thoughtful, elegant, unflappable Andrea Pirlo.

The pair formed the backbone of a memorable AC Milan team for more than a decade and helped Italy win the 2006 World Cup.

On Sunday, the old chums will face each other on the touchline for the first time as Pirlo's Juventus host Gattuso's Napoli in Serie A.

Napoli have made an impressive start to the season, winning both of their opening games, while Juve, chasing a 10th successive Serie A title, began with a win and a draw.

While the coaches are good friends, there is no love lost between their teams. More than any other fixture in Italian football, it has come to be seen as a clash between the rich, industrial wealth of the north and the much poorer south.

Napoli have enjoyed the upper hand in the last two meetings, beating Juventus 2-1 in Serie A and winning last season's Coppa Italia final on penalties after a 0-0 draw.

In coaching terms, Gattuso, 42, has had a head start on his former team mate. He is already at his sixth club since embarking on his new career at Swiss side FC Sion in 2013, where he was unceremoniously sacked after three months.

The 41-year-old Pirlo, meanwhile, will be in charge of only his third game as a coach, having surprisingly been handed the reins in August following the dismissal of Maurizio Sarri.

"He's lucky to be starting at Juventus, but this profession is one where a great playing career is not enough," warned Gattuso. "You have to study, work hard, and you don't get much sleep."

Despite their very different playing styles, the two players complemented each other perfectly at Milan.

"When I saw him play it made me think I had to change profession," Gattuso once said. "I understood what I had to do, and he took care of the rest. He helped me much more in my career than I did him."

They would also play pranks on each other, with Gattuso's short temper making him a prime target.

In his autobiography, Pirlo told how he and Italy team mate Daniele De Rossi once doused Gattuso with a fire extinguisher and recalled Gattuso attacking him and other Milan players with a fork, causing at least one to miss the game through injury.

Pirlo added: "We'd get out of his way when he got mad but once he'd calmed down and gone to his room, we'd come back out, pile up the sofas in front of the door and block his exit."