Dutchman Matthijs de Ligt gave Juventus the lead towards the end of an even first half, but Ilija Nestorovski equalised shortly after the break and Seko Fofana netted an injury time winner to stun the visitors.
The Old Lady remain six points ahead of second place Atalanta with three games left to play, so the result only prolongs the wait for yet another Scudetto triumph being celebrated, but is a blow nonetheless.
After beating Juventus just five times previously in the top flight and the last coming a decade ago, it was also Udinese’s first victory on home turf since defeating Sassuolo in January.
A booking for Juventus’ Aaron Ramsey inside 30 seconds of kick off indicated it was going to be a match/performance full of industry rather than artistry and the most notable early efforts on goal from both teams came from players on their own team.
The Zebrette nearly took the lead on eight minutes when Danilo headed a Ken Sema cross against the post and, five minutes later, defender Bram Nuytinck watched with relief as his back pass brushed the upright.
Looking to surpass Felice Borel’s record of 31 goals in a single Serie A campaign for the Old Lady, Cristiano Ronaldo had a handful of speculative attempts on Juan Musso’s goal, before an unlikely source provided the breakthrough.
Striding forward from defence to collect an Udinese clearance, De Ligt nudged the ball ahead of himself and unleashed a stunning low drive from 30 yards into the bottom corner with his right foot on 42 minutes.
After watching the referee wave away a penalty claim by Zebrette captain Rodrigo de Paul moments earlier, the hosts must have been thinking there would be no points to lift their relegation fears.
However, within seven minutes of the restart, a wonderful passing move ended with Nestorovski meeting another brilliant Sema cross with a diving header that flew past Wojciech Szczesny.
While the goal brought a sense of urgency to the second half, it looked as though it would only result in the sides playing out a faster paced stalemate, as both sides failed to create clear openings as the minutes ticked by.
With the match deep in injury time, though, Fofana found himself driving towards the Juventus goal and after breaking into the box slipped the ball under the body of the approaching Szczesny to win the game.