UNITED KINGDOM: Jose Mourinho accused Antonio Conte of trying to humiliate him during his nightmare return to Stamford Bridge in which Chelsea thrashed Manchester United 4-0.
And the row continued into the tunnel after a member of Mourinho's backroom staff refused to shake Chelsea head coach Conte's hand and was confronted by one of the Italian's assistants.
Goals from Pedro, after just 30 seconds, Gary Cahill, Eden Hazard and N'Golo Kante completed a miserable first return to Chelsea for Mourinho since he was sacked by the club last December.
The flashpoint between the pair came at the final whistle after Conte had gesticulated for the Stamford Bridge crowd to start singing for their team with time running out.
Speaking in Italian, Mourinho used the full-time handshake to tell Conte that his cheerleading had been an attempt to humiliate him in front of his former fans.
Conte denied that was his motivation, insisting he felt his team deserved the adulation of the crowd.
It was not just Manchester United manager Mourinho who did not take the defeat well. A member of his staff ignored the outstretched hand of Conte at the final whistle and was involved in a heated argument in the tunnel.
Both Mourinho and Conte refused to confirm what was said, but neither man denied the version of events that was put to them.
Conte said: "I think private conversations must remain private.
"I think that, today, it was right to call our fans in a moment I was listening only to the supporters of Manchester United at 4-0. So I called the fans to give the players a great clap after this kind of performance.
"We live with emotions. If you want to cut the emotions, we can stay at home and I will change jobs.
"It's important for our fans to push in every moment of the game. When the players deserve it after this performance, it's right to receive a great clap from the fans."
On the incident with Conte, Mourinho said: "You know me. I spoke to Conte, not to you. I'm not the kind of guy to come here and share with you things I don't want to share. I have no comment."
Ironically, Mourinho called for the Stamford Bridge crowd to be louder on numerous occasions during both of his spells at the club.
The Chelsea fans left it until their team were four goals ahead to start a rendition of "Jose Mourinho" in tribute to the club's most successful manager and the 53-year-old added: "I didn't feel it [the reaction from the crowd]. I was in the game. For sure it was not negative. It had no reason to be. What would they have against me, or me against them? Nothing. Everything was calm."
Chelsea's players were clearly delighted to beat their old boss and took the opportunity to rub his nose in it by posting pictures on social media of the entire team celebrating in the dressing room.
"I think it's right to celebrate when you win," said Conte.
"When you work very hard and win, it's important to celebrate. But I have already told my players that United is the past. Now we must be focused on Wednesday because there is another important, tough game against West Ham. It's important to celebrate this evening, but then to start to focus on another game."
There was a further blow for United when central defender Eric Bailly was forced off with suspected knee ligament damage.
"He is injured and I'm afraid he's badly injured," said Mourinho.
"In his knee. The injury is in the ligament area. He feels that is really bad."