Jose Mourinho finally appears to have met his match - and his name is Antonio Conte.
Arsene Wenger and Sir Alex Ferguson both have previous with the Portuguese but very rarely is he outclassed by a manager twice in one season.
Something about Conte clearly gets under Mourinho's skin. Back in October, the pair clashed when Conte produced an over-the-top celebration to Chelsea's fourth goal in a 4-0 win.
They were at each other's throats again during Monday night's FA Cup quarter-final clash, with Conte reacting angrily to Mourinho kicking the ball in his direction.
The Italian, after watching Antonio Valencia hack down Marcos Alonso, stormed over to United's manager and hurled verbal abuse at him.
Mourinho and Conte were eventually separated by the fourth official but, according to Marca, their row was far from over.
They claim the managerial pair continued to argue down the tunnel at half-time and had to be stopped by Chelsea and United's players, who acted as peacemakers to calm the situation.
Marca's report goes some way to explaining why Mourinho didn't shake Conte's hand after the game, despite what the Portuguese said on the matter.
"If I see him (Conte) here, I shake [his hand]," Mourinho said when asked why he didn't shake hands with Conte. "I didn't because I thought my players deserved my action immediately.
"Our supporters also deserve thanks to them, so it was that.
"I can promise you, if I see him there (outside the dressing room), I shake his hand. I have nothing to say to him at all, but to shake his hand, for sure, I will do that."
Mourinho also aimed a subtle dig at Conte and Chelsea's fans by explaining that, until the Italian wins four Premier League titles at Stamford Bridge, he will always be No.1.
"The fans can call me what they want," Mourinho added. "I am a professional. I defend my club.
"Until the moment [Chelsea] have a manager that wins four Premier Leagues for them, I'm the No.1.
"When they have somebody who wins four Premier Leagues for them, I'll be No.2. For this moment, 'Judas' is No.1."
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