Juventus were on track for the treble in early February. Now, their very superiority in Italy is under threat.

Wednesday's Coppa Italia final defeat to Napoli might only have come on penalties, but few could argue the Bianconeri deserved better, save for goalkeeper Gianluigi Buffon.

Napoli, missing the suspended semi-final hero David Ospina, were the only team with a clear game plan in the eerily quiet Stadio Olimpico. They had 15 shots to Juve's 13 and seven on target to the Serie A leaders' three, despite slightly less possession.

Theirs was an obvious ploy, one they have followed rigidly since Gennaro Gattuso took charge in December: a defiance off the ball, a commitment to counter-attacking but only at the right moment. Catenaccio for the 21st century.

The concern for Juve is that, a year after Maurizio Sarri became head coach, it's hard to know what their plan is.

Their chances were scarce throughout, the best a snapshot from Cristiano Ronaldo five minutes in. At the other end, they were indebted to Buffon, the 42-year-old flying across his line to keep out Diego Demme, Lorenzo Insigne, Dries Mertens, Matteo Politano and, somehow, Nikola Maksimovic and Eljif Elmas with a spectacular double-save in second-half injury time.

He was largely helpless in the shoot-out as Napoli scored all four from the spot, after Paulo Dybala's effort was saved by Alex Meret and Danilo stalled, stuttered and smashed his over the crossbar.

Juve have never looked settled under Sarri, but results have been mostly sufficient. They are top of Serie A by one point ahead of the return of Italy's top flight this week, but they have won only four of their past 10 games in all competitions, a run that includes a 1-0 loss at Lyon that leaves their Champions League hopes under threat for another season.

Sarri, having lost the Supercoppa Italiana to Lazio already this season, was upset this week by suggestions he has not been a successful coach in Italy, referring to his eight promotions from the lower leagues.

That's not enough in Turin. Sarri was hired after reaching two finals (winning one) in his sole season with Chelsea, a man revered by sections of Italian football for a stylistic way of winning not least at old club Napoli, brought to Juve to marry domestic dominance with European success in a manner to make fans proud. Right now, they are far from that.

Napoli fully deserved their first trophy since 2014, none more so than Gattuso, who lost his sister only weeks ago. His appointment was a gamble after a tricky spell in charge of Milan, but one that has been rewarded. It's not all his fault, but Sarri's own season is at risk of unravelling.