Torino put the brakes on Juventus' charge towards the Serie A title by winning the Turin derby for the first time in 20 years.
Three points from their rivals at the Stadio Olimpico, coupled with a negative result for nearest challengers Lazio, could have seen Juve open up an 18-point lead with only six games remaining.
Andrea Pirlo did put them on the right track with a sublime free-kick in the first half but Matteo Darmian pegged the reigning champions back just before the break and Juve old boy Fabio Quagliarella forced his recent employers to wait a little while longer for the championship by settling a 2-1 win for the Toro -- their first derby success since 1995.
Knowing victory downtown would effectively seal their fourth straight Scudetto triumph no matter what second-placed Lazio achieved against Chievo, Juve needed to start well.
Yet Alvaro Morata's early sighter was poor and Torino were soon on the counter-attack with Quagliarella giving Gianluigi Buffon food for thought with a daisy-cutter.
Pirlo provided Alessandro Matri with a superb pass in the 12th minute but Nikola Maksimovic put the striker off before he could pull the trigger.
Juve struggled to make further inroads with Torino bossing possession, yet a foul conceded on the edge of the Granata box in the 35th minute would cause them serious damage.
Pirlo stepped up to take the subsequent free-kick and duly flighted a trademark finish into Daniele Padelli's top corner.
Although Torino were rattled, Quagliarella steeled himself and almost got the better of Buffon from a one-on-one. The offside flag confirmed he would not have scored a valid goal anyway.
Still the hosts pushed forward and they got their reward on the stroke of half-time as Darmian fired a confidence-boosting leveller.
The ever-impressive Quagliarella shrugged off the challenge of Leonardo Bonucci to serve the onrushing full-back, who controlled before beating Buffon with a cool right-footed strike.
Pirlo looked to re-establish Juve's lead when play resumed, again from a free-kick, but this time -- from a greater distance -- he could only rattle a post.
Minutes later, Quagliarella got the goal his first-half performance merited to boost Torino into a shock lead just before the hour mark.
Darmian's low cross completely fooled the Juve defence, leaving Quagliarella all alone in front of Buffon for an easy conversion. Suddenly the title looked far away once again.
Arturo Vidal looked for an immediate answer with his header on Roberto Pereyra's cross fizzing just wide yet, in the 72nd minute, Torino went even closer through Quagliarella and another one-on-one.
Juve remained on the ropes and only the quick-thinking of former Torino defender Angelo Ogbonna kept Quagliarella from doubling up after he controlled Giuseppe Vives' clever assist.
As the game entered its final 10 minutes Juve grew more desperate and Matri needed a cooler head when attempting to fool Padelli with a cross-cum-shot.
He did hit the post and, in the 83rd minute, Padelli made a brilliant reflex save against Stefano Sturaro after Pirlo put the young midfielder through.
Full-time arrived, with the only crumb of comfort offered to the Bianconeri coming in the form of news from Rome, where Lazio had been held to a 1-1 draw by Chievo.
The gap now stands at 14 points with 18 available to both title rivals.