Juventus' stranglehold on the Scudetto loosened even further after a 1-0 defeat at home to struggling Benevento left the Bianconeri 10 points adrift of Serie A leaders Inter Milan.
The Turin giants were looking to make up ground on their rivals but fell behind in the 69th minute when Arthur's cross-field pass across his own area was cut out by Adolfo Gaich, who coolly slotted beyond Wojciech Szczesny.
Cristiano Ronaldo had earlier volleyed into the net but it was ruled out for offside while the Portuguese was thwarted on more than one occasion by visiting goalkeeper Lorenzo Montipo as Benevento held on for a famous win.
While Benevento ended an 11-game winless run to move seven points clear of the relegation zone, Juve's hopes of a 10th successive league title suffered a further blow, intensifying the pressure on head coach Andrea Pirlo.
Atalanta moved level on points with Juve after a 2-0 victory at Hellas Verona, who crashed to a third successive defeat following first-half goals from Ruslan Malinovskyi, from the penalty spot, and Duvan Zapata.
Atalanta have played a game more than the defending champions but this was a satisfying domestic return following their elimination in the Champions League earlier in the week at the hands of Real Madrid.
Torino remain just a point above the bottom three after a 1-0 loss at Sampdoria, where Antonio Candreva scored the only goal of the game, while Adam Marusic's effort helped Lazio win at Udinese by the same scoreline.
