Sampdoria became the only team to beat Juventus twice in the league under Antonio Conte as it secured a 3-2 victory over the newly-crowned Serie A champion on Saturday.
Eder, Lorenzo De Silvestri and Mauro Icardi helped Sampdoria come from behind after Fabio Quagliarella had scored against his old team.
Emanuele Giaccherini reduced the deficit in stoppage time.
Juventus striker Nicklas Bendtner fractured his wrist in the game and will have an operation on Sunday.
"I want to say a great thanks to these lads who have done something amazing in these two years," Conte said. "There's a bit of a bad taste but it was a nice night. It's a pity only for the 100th injury of Bendtner who really had an unlucky season.
"We should only continue to thanks these lads for their extraordinary achievements. It's disrespectful towards them to talk about the transfer market today. From tomorrow the club with start evaluating things."
Earlier, Sassuolo clinched promotion to Serie A for the first time in its history, finishing as Serie B champions following a last-gasp 1-0 victory over third-placed Livorno.
Hellas Verona joined Sassuolo as runners-up after a goalless draw against fourth-place Empoli.
A playoff involving the teams which finished third to sixth will determine the third team to get promoted.
The only Serie A game to take place on Saturday was at Genoa, with the nine final games of the season all taking place on Sunday.
Juventus took the lead in the 25th minute when Quagliarella controlled a delightful long ball over the defense from Andrea Pirlo and slotted it into the bottom right corner.
Samp drew level six minutes later when it was handed a penalty after Giorgio Chiellini was adjudged to have pulled back Icardi. Eder converted, drilling into the bottom left corner.
De Silvestri headed in a corner to put Samp in front in the 58th, moments after a fingertip save from goalkeeper Junior Da Costa had denied Simone Padoin after the Juventus midfielder had been sent clear through.
Iscardi bundled in Marcelo Estigarribia's cross from close range in the 75th to extend Sampdoria's advantage.
There was another moment of controversy minutes later as the referee awarded Juventus but then changed his mind, apologizing to the players and repeatedly saying "I made a mistake."
Chiellini protested vehemently as Shkodran Mustafi appeared to have clattered into Quagliarella.
Juventus was left in 10 men for the final minutes as substitute Bendtner had to come off after landing heavily on his arm. Conte had already made his three changes.
It still managed to pull one back late as Giaccherini volleyed in Stephan Lichtsteiner's cross.
Champions League finalist Bayern Munich is the only other team to have beaten Juventus twice since Conte took charge two years ago.
"Juve's quality is beyond doubt, so it's probably a coincidence that we won both games against them," Sampdoria coach Delio Rossi said. "It remains a great achievement to have beaten the champions of Italy.
"I know that I will lose some players and if Icardi receives an important offer then he will leave Sampdoria. As far as I know, unfortunately, the offers have come in."
Elsewhere, Simone Missiroli scored the decisive goal for Sassuolo with practically the last kick of the game after his team had been reduced to nine men, while Livorno also had a player sent off.
Sassuolo defender Luca Antei was sent off shortly before the hour after picking up his second yellow card. Livorno goalkeeper Vincenzo Fiorillo was then shown a straight red 15 minutes from full time for throwing Domenico Berardi to the ground, and the Sassuolo striker was also sent off his reaction.
Sassuolo is a small town of around 40,000 inhabitants, near Modena in northern Italy, and its team was playing in the fourth division seven years ago. It was steered into Serie B in 2008, under current AC Milan coach Massimiliano Allegri.
It had lost in the playoff in two of the previous three seasons. Livorno and Empoli will host Brescia and Novara respectively in the playoff semifinals.
The three promoted teams will replace Pescara, Siena and Palermo, which have been relegated from Serie A.