Litmus test: Juventus clash will show how far Montella's Milan has come

The San Siro is sold out for a game that matters.

AC Milan enters Saturday's match against Juventus on the heels of a five-match unbeaten run and on a wave of optimism.

It's not something to be taken for granted.

For the past few years, this fixture has taken on less and less meaning. The rivalry, once one of the fiercest in Italy, became lopsided: Juventus has beaten the Rossoneri nine times in a row.

But manager Vincenzo Montella may have the answer.

What was missing for so long at the San Siro was fighting spirit. Besides all the misplaced passes and the poor defending, there was an absence of will. There were simply players at Milan who should never have been there.

Spectators finally saw that burning desire on Oct. 2. Facing a 3-1 deficit to Sassuolo, Montella's men led a three-goal charge to win 4-3. Milan pulled off the comeback with a brilliant second-half performance that included a blistering goal from 18-year-old midfielder Manuel Locatelli.

Related - Watch: Locatelli's screamer leads AC Milan comeback vs. Sassuolo

That may have signaled a change in the club's overall attitude. This is now one of the youngest teams in all of Serie A as opposed to one of the oldest, a squad full of players who want to impress. M'Baye Niang and Suso spent so much time in purgatory, on loan, or out of mind, and now they are taking their chance as protagonists in this side.

Carlos Bacca was also something of a cast-off in the summer, so close to leaving Milan as a financial sacrifice for the cash-strapped club. He rejected a move to West Ham, and a Champions League club failed to produce an offer for him.

In the end, he stayed, and he's scoring goals.

Bring the whole package together, and it becomes clear that Montella has coaxed something out of a flailing team without the help of big signings. Apart from promising striker Gianluca Lapadula and stop-gap defender Gustavo Gomez, Montella has made the best of what he's inherited.

Some reinforcements could arrive soon - Milan's incoming Chinese owners have promised €100 million in investments during the January window - but there's at least a foundation here.

Milan is not playing world-class football by anyone's imagination. Not even the best in Serie A. There are still an alarming number of back-passes and lapses in concentration.

But there's something resembling a possession-based brand of football. Aimless for years, Milan actually has a style of play.

Its share of the ball has only grown in recent showings, and it's patient in build-up play. It's not trying to force a pass, or look for a man that can't run onto the ball. Instead, Montella clearly has his players looking for a quick switch in play, and the likes of Suso have the feet to wriggle around defenders and wallop a shot on goal.

It's not just up front: There's a growing relationship at the back between Alessio Romagnoli and Gabriel Paletta. At 21 and already coveted by Chelsea, Romagnoli is very much the future of Milan's defence, but old fox Paletta has surprised onlookers with his aerial ability and solid marking. Together they have produced more clearances (99) than any other defensive duo after eight Serie A matches.

And the calmness and poise of 17-year-old Gianluigi Donnarumma helps matters. Standing at 6-foot-4, Donnarumma can reach almost any ball, and he's quick to react. He's bailed out Romagnoli and Paletta on a few too many occasions, but it says something that a teenager can do that on a consistent basis.

Ahead of Milan is the toughest test of the early season. Juventus is Serie A royalty, the golden standard of Italian football.

The Bianconeri have the firepower to dent the host's hopes. Gonzalo Higuain and Paulo Dybala are beginning to find the net with ease, and the more attack-minded Miralem Pjanic has been released from a frustrating deep-lying role. They've also kept clean sheets in five of their past six games, despite Leonardo Bonucci's personal situation and Giorgio Chiellini's injury.

A win over the five-time defending champion would validate Milan's budding project, and the fans may yet have a reason to fill up the San Siro again.