AC Milan's Sulley Muntari was already celebrating after heading the ball over the line, oblivious to the fact that officials had waved play on even though replays showed the ball was a good metre inside the goal.
Had the goal counted, AC Milan would have gone 2-0 ahead at a point where they were dominating the game and there might well have been no way back for a ragged Juventus.
Instead, Juve regrouped to force a 1-1 draw and in doing so provided another boost for the case in favour of goal-line technology, currently being tested by football's governing body FIFA.
Juventus stayed one point behind Serie A leaders Milan with a game in hand, whereas a defeat would have left them four points adrift with the psychological blow of having lost their unbeaten record this season.
AC Milan coach Massimiliano Allegri was typically philosophical about the incident.
"The best thing would be not to talk and to stay quiet, divine justice can punish everyone for what they say," he said.
"If it had been 2-0, the game would have been well under control especially as we were on top.
"Maybe they painted the goal line took thick," he added.
Players from both sides agreed that the ball was in, including Juventus goalkeeper Gianluigi Buffon.
"I wasn't aware at the time of my position or of Muntari's shot. Afterwards, I saw in the pictures that the ball had gone in," he said.
"But I must be frank and say that if I had realised, I would not have helped the referee."
Juventus also pointed out that they had a goal harshly disallowed just before their equaliser.
"There were refereeing mistakes today, one for their goal when the ball went in, and then when we had a goal disallowed for offside," said coach Antonio Conte.
"The best thing has been the match. As for the rest, everyone has to improve, including myself."
