It's difficult to predict how football will look back on Massimiliano Allegri's trophy-laden reign at Juventus in a few years' time.
Will people say his success was a given taking into account Juventus' considerable resources compared to their Italian rivals? Will people argue that his reign was even unremarkable given his failure to win the Champions League? Or, will people argue that he was the most successful manager in the history of the club and that his time at the Allianz Stadium marked a golden period at Juventus?
Regardless of what judgements people may make, the stats still remain. He won the Scudetto, decisively in every season he managed the club, won the domestic double for four seasons in a row and holds the highest win percentage in the club's history.
This summer, however, the Juventus hierarchy felt the need for a change. Motivated by a desire to play a more attacking style of football, they appointed Maurizio Sarri with the expectation also, given his success in the Europa League with Chelsea last season, that he can be the man to finally deliver them that elusive Champions League trophy.
It was a bold move by Juventus. They had found stability under Allegri in his five-year reign and some felt that he would have been capable to deliver the Champions League to the Old Lady. Unfortunately for them, they couldn't have picked a worse time to make this significant change.
Juventus probably owe their domestic success over the last eight years, in part, to the downfall of the Milan clubs. The 2010s have not been kind to Inter and Milan, with neither club really challenging for trophies and failing, at times, to even qualify for the Europa League. Meanwhile, Juve's nearest rivals, Roma and Napoli, couldn't possibly compete with Juventus in terms of resources.
That's all changed this summer, however. Milan and Roma are still very much benign, but Napoli and particularly Inter, are looking like genuine title challengers this season.
Napoli, with Carlo Ancelotti at the helm, have had a very successful summer. They kept Kalidou Koulibaly and found a new defensive partner in Roma's Kostas Manolas, himself a world-class defender. I Partenopei also completed a coup in signing PSV's Hirving Lozano, who impressed on his debut against Juventus.
Inter have also had a summer of change. They ditched Luciano Spalletti, who had returned the Nerazzurri to the Champions League after a six-year absence, and replaced him with Antonio Conte, one of the best managers working today. They also completed excellent deals for the likes of Romelu Lukaku, Alexis Sanchez and Diego Godin.
The signing of Romelu Lukaku, in particular, is a sign that Inter intends to return to being among Europe's elite. The Nerazzurri paid a club-record €80m fee for one of the best forwards on the continent and he has already repaid them with two goals in his first two games. It's the most positive Inter fans have felt in a while and they have much reason to be.
Given Juventus' experimentation with a new coach despite the stability and success Allegri bought to the club, Inter and Napoli will really feel that they can mount a proper challenge for the Scudetto this season.
Napoli pushed Juventus all the way when they visited Turin last week, coming back from three goals down and only falling to defeat after an unfortunate Koulibaly own goal, while also registering a solid opening day win away at Fiorentina.
Inter, meanwhile, have won their two opening games, including an emphatic 4-0 win over Lecce in Conte's first competitive match in charge of the club, while their new signings have impressed in what feels like a completely different Nerazzurri side.
With these factors in mind, Juventus will surely be looking over their shoulder this season. Serie A, on the surface at least, is no longer a one-horse race.