A first-half penalty was enough to earn champions Inter Milan a crucial 1-0 win at Juventus on Sunday, dragging Simone Inzaghi's side back into the Serie A title race.
Juve wasted a host of chances in the opening period, with veteran defender Giorgio Chiellini guilty of missing the most glaring of them, and their profligacy proved costly as Inter earned a penalty in first-half stoppage time following a VAR review.
The home side were furious at the awarding of the spot kick, but felt justice was done when Wojciech Szczesny saved Hakan Calhanoglu's penalty, only for the referee to order a retake, which the Turkish midfielder converted to give Inter the lead.
The goal did not change the balance of play, however, as Paulo Dybala and Dusan Vlahovic both went close to an equaliser in the second half, before Inter goalkeeper Samir Handanovic tipped Denis Zakaria's brilliant strike onto the post.
It remained one-way traffic until the final whistle, but Juve, who had 23 shots at goal to Inter's five, could not make the pressure pay, as the visitors held on to seal all three points.
Juve's first league defeat since November leaves them on 59 points in fourth in the standings, four points behind Inter in third, with the champions now three behind leaders AC Milan.
Juventus's run of 16 league matches unbeaten prior to Sunday's Derby d'Italia had seen them claw themselves back into the top-four battle and also the title race.
Inter's run of one win in their previous seven league games had aided Juve's task, and it looked like Massimiliano Allegri's side would get the victory that would have seen them climb above the champions as they dominated from the off.
Chiellini was denied by the crossbar from close range early on, with Alvaro Morata and Dybala both failing to find the target from good positions.
Further openings came and went before chaos erupted surrounding the penalty award. After a second look on the pitchside monitor, the referee ruled Denzel Dumfries had been fouled in the penalty area.
Szczesny, looking to save his fourth successive Serie A penalty, guessed correctly, but Juve's Dutch defender Matthijs de Ligt had encroached in the penalty area before the kick had been taken, so Calhanoglu got another chance, which he did not pass up. The Juve protests went on for a while afterwards.
Big-money January signing Vlahovic should have levelled after a smart turn early in the second, as should Dybala from another good position, but it just would not go in for the hosts.
Inter dug in late on and survived several other scares, but defended for their lives, celebrating the victory on the final whistle knowing just how important a first win away at Juventus in a decade could be come the end of the season.
Elsewhere in Serie A on Sunday, Henrikh Mkhitaryan's first-half goal was enough to earn AS Roma a 1-0 win at Sampdoria to move Jose Mourinho's side up to fifth, while Udinese pulled clear of a relegation zone with a 5-1 thrashing of Cagliari.