Cristiano Ronaldo scored for the 10th consecutive Serie A game for Juventus on Saturday but could not prevent the Italian champions from slipping to a surprise 2-1 defeat at Hellas Verona.
An eventful first half saw the visitors twice denied by the woodwork; Douglas Costa had a fierce shot tipped onto the crossbar by goalkeeper Marco Silvestri, and Ronaldo curled an effort against the post.
Verona were threatening, though, and they had a goal ruled out for offside by VAR when Miguel Veloso's free-kick was headed past Wojciech Szczesny by Marash Kumbulla.
Ronaldo struck the opening goal on 65 minutes. The Portugal international swapped passes with Rodrigo Bentancur and managed to fend off Amir Rrahmani before firing a low shot past Silvestri.
Yet Verona hit back with two goals in 10 minutes to snatch all three points. Fabio Borini took advantage of some poor defending to curl the equaliser before Giampaolo Pazzini won it from the penalty spot after a handball by Leonardo Bonucci.
Juventus manager Maurizio Sarri kept faith with the same team that beat Fiorentina 3-0 last time out in Serie A, meaning Paulo Dybala was again on the bench. Verona made just one change for the visit of the champions, bringing in Sofyan Amrabat for Valerio Verre.
Verona enjoyed a bright first half and caused the visitors problems. A full-stretch Szczesny tipped an effort from Davide Faraoni over the crossbar after just 10 minutes (UK video only):
Verona almost scored from the resulting corner when Matteo Pessina's volley hit an unmarked Amir Rrahmani at the far post and bounced just wide.
The hosts thought they had scored when Kumbulla's header beat Szczesny on 24 minutes. The Juve goalkeeper managed to parry the effort but could not prevent it from rolling into the back of the net.
However, the goalkeeper was granted a reprieve when the VAR check decided that Kumbulla had been just offside when Veloso played the ball into the box from a free-kick.
Juventus grew into the game and had plenty of chances to break the deadlock. Gonzalo Higuain saw an effort blocked in the opening minutes, while Costa's effort was brilliantly tipped onto the crossbar by Silvestri.
Ronaldo was also denied by the woodwork after cutting in from the left and firing across Silvestri and onto the post 10 minutes before half-time. The Portugal international also headed another effort off-target as the visitors ended the opening 45 minutes on top.
Sarri sent on Dybala for Higuain just before the hour in search of a goal, and the visitors looked more of a threat with the lively Argentina international on the pitch.
The opening goal eventually came through a record-breaking strike from Ronaldo. The forward ran from the halfway line and slotted home to earn a new club record of scoring in 10 consecutive Serie A games:
Verona hit back 10 minutes later through Borini's second league goal of the season, though. A poor touch from Miralem Pjanic gifted the striker possession inside the penalty area, and he curled a brilliant finish past Szczesny for the equaliser.
The hosts then went ahead from the penalty spot after Bonucci was penalised for handball by VAR when trying to head clear from a corner.
Pazzini kept his composure to fire his penalty past Szczesny and claim a famous win for Ivan Juric's side while condemning Juve to a third defeat in their last five Serie A away matches (UK video only):
The result means Sarri's men miss the chance to extend their lead at the top of the table to six points and offers Inter Milan the chance to move level on points at the top of the table if they beat AC Milan on Sunday.
Juventus play AC Milan in the first leg of their Coppa Italia semi-final on Thursday at the San Siro. Verona return to action on Sunday against Udinese in Serie A.