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.
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.
Juventus took the lead in the 25th minute when Quagliarella controlled a delightful long ball over the defence 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 Nicklas 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 at the death as Giaccherini volleyed in Stephan Lichtsteiner’s cross.
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.
Sociedad, Valencia continue battle for 4th place: La Liga
(PhatzRadio / CBC Sports) — Real Sociedad came back to win 2-1 at Sevilla and Valencia beat Getafe 1-0 on Saturday as both teams remained locked on points in their fight for a fourth-place finish in the Spanish league.
Sociedad remained ahead of fifth-place Valencia on head-to-head goal difference and in control of Spain’s last Champions League spot with two rounds to go.
The Basque side fell behind 10 minutes in at Sanchez Pizjuan Stadium when Sevilla midfielder Ivan Rakitic slotted in a back pass from Geoffrey Kondogbia.
But Rakitic’s own goal when he headed a free kick into his team’s net in the 16th levelled the score, and striker Imanol Agirretxe swept in Carlos Martinez’s lobbed pass to give Sociedad the lead for good in the 24th with his 13th goal of the season.
Both sides created several chances in the second half, but neither could finish them off.
Sevilla’s Jose Antonio Reyes was dismissed after halftime with a direct red card for protesting a decision by the line judge while warming up on the sideline.
“We’re happy because it’s very hard to win here,” said Sociedad coach Philippe Montanier. “In their previous nine home games only Atletico (Madrid) had won here. It was a tough game. We played well in the first half, and then in the second we tried to sit farther back and score on the break. But we had difficulties with their set pieces and had to hold on until the end.”
Valencia outplayed Getafe throughout but only edged past the hosts thanks to Jeremy Mathieu’s first-half goal.
Mathieu scored with a deft volley off a pass from Ever Banega in the 44th, firing the ball into the net from outside the area.
Getafe never threatened to draw at its Alfonso Perez Coliseum, with goalkeeper Miguel Moya saving the hosts from a heavier defeat.
Valencia coach Ernesto Valverde, who after taking over has led the team up the table to challenge for a berth in Europe’s top-tier competition, played coy when asked if he was any closer to extending his contract past this season.
“I don’t know if I’m going to have a meeting next week (with the club),” Valverde said. “The most important thing now is the game against Granada. If I speak or not with the club could be interesting to the general public, (but) if I consider that transmitting knowledge of it would hurt the team I won’t say anything.”
Elsewhere, Granada went a long way toward ensuring its third straight season in the first division by rolling over 10-man Osasuna 3-0 after Brazilian defender Siqueira set up one goal and scored another.
Siqueira passed for unmarked striker Youssef El Arabi to poke the ball under goalkeeper Andres Fernandez for Granada’s first goal in the 23rd.
He then converted a penalty kick in the “Panenka” chipped style in the 80th after Fernando “Nano” Macedo was sent off when he fouled Yacine Brahimi from behind with only the goalie to beat. Diego Buonanotte added the hosts’ third goal in stoppage time.
Granada stayed undefeated in five consecutive games and rose seven points clear of the relegation zone, while Osasuna was left four points above the drop before three of the four teams below it in the standings play this round.
On Sunday, new league champion Barcelona plays Valladolid without injured top scorer Lionel Messi. Barcelona can match Real Madrid’s record haul of 100 points from last season if it wins its remaining three matches.
Also on Sunday, it’s: Levante vs. Rayo Vallecano, Real Zaragoza vs. Athletic Bilbao, and Deportivo La Coruna vs. Espanyol.
Last-place Mallorca hosts Real Betis on Monday.
Madrid, Atletico, Malaga, and Celta Vigo already played their fixtures for this round last week to make room in the calendar for the Copa del Rey final on Friday, when Atletico beat Madrid 2-1 in extra time for its 10th cup.
Atletico celebrated its first win over its crosstown rivals in 26 matches dating back to 1999 with a parade through the Spanish capital on Saturday.
In the second division, Elche earned promotion on Saturday after Alcorcon drew 1-1 at Barcelona B.