Juventus boss Massimiliano Allegri claimed pressure from AC Milan's players persuaded referee Nicola Rizzoli to rule out a Miralem Pjanic goal in his side's controversial 1-0 defeat at San Siro.
Manuel Locatelli's superb second-half strike ultimately secured the win for the hosts, their first over Juventus in Serie A for four years, but the visitors appeared to have reason to be aggrieved.
An offside Medhi Benatia did not seem to be interfering with play when Pjanic's 35-yard, first-half free-kick flew in and the goal was originally allowed to stand.
But the decision prompted a storm of protests from the Milan players and after consulting with his assistants, the referee reversed his decision, leaving Allegri less than impressed.
"They did well to score and we were unlucky," he told Mediaset Premium.
"We played well on a technical level and we had scored, but it was disallowed.
"These things happen. Unfortunately the goal was valid, but Milan's protest made the referee doubt his own decision.
"We should, as teams, focus on playing football and not put more pressure on to the referees.
"I want to understand whether it was the referee or the assistant who reversed the call."
Juventus remain top of the table despite suffering their second league defeat of the season and although their lead has now been cut to two points, Allegri insisted he was not overly concerned.
"I have to compliment my team as we put in a good performance against an organised Milan that gave their all," he said.
"This defeat does not change the course of our season. In terms of performance, I have no complaints with my lads. This loss must not trouble us. We controlled the game and had many shots on goal, reaching the penalty area with good team moves.
"Milan had one shot on goal in each half, but played in a determined and tough fashion and Locatelli scored a great goal."
Juventus return to league action on Wednesday when they host Sampdoria.