Napoli boss Carlo Ancelotti was "offended" and "disappointed" after he was sent to the stand as Atalanta twice came from behind to secure a 2-2 draw at the San Paolo Stadium.
Napoli took an early lead through Nikola Maksimovic, only for Remo Freuler to level with a clever shot through the legs of goalkeeper Alex Meret.
The home side regained the lead through an Arkadiusz Milik strike at the start of the second half and looked to be heading for all three points before Josip Ilicic's 86th-minute equaliser.
The Napoli players and coaches were incensed by the referee's decision not to award their side a penalty just after the equaliser, and manager Ancelotti was shown a red card.
Ancelotti told a press conference reported by the club website: "This evening for the first time I prefer to speak little, I feel offended in my seriousness and I am disappointed."
"Honestly we should not even comment on it. The defender (Simon Kjaer) is not interested in the ball and goes directly to (Fernando) Llorente. A clear penalty.
"For me there was no need for VAR but it is absurd that the referee did not go to see the images."
On the decision made by the referee to send him to the stands, the 60-year-old said: "I repeat that I feel offended and attacked.
"On the match I can say that we deserved to win. I am satisfied with the game, it was a complete performance."
Atalanta manager Gian Piero Gasperini disagreed with Ancelotti, even though his initial reaction was that Napoli should have been awarded a spot-kick.
"From the pitch, I thought it was a penalty. Then, seeing the images, I saw a big elbow to Kjaer's face," Gasperini told Sky Sport Italia.
"The images are very clear. Whoever was in the VAR booth confirmed what the referee saw, but I'm rightly biased.
"We struggled to control Napoli at first. They immediately created three chances and went ahead soon after.
"Napoli have great pace in their team, but little by little we managed to get the game back in hand, creating good chances and drawing level with them."