Antonio Conte and Jose Mourinho had to be separated as N'Golo Kante's strike sent Chelsea into the FA Cup semi-finals with a 1-0 win over Manchester United at Stamford Bridge.
Fourth official Mike Jones had to intervene as Conte and Mourinho had a frank touchline exchange during a feisty contest in which United had Ander Herrera sent off for two bookable offences after 35 minutes.
Kante's second Chelsea goal six minutes into the second half secured a quarter-final win for the Premier League leaders, who won for a club record 13th successive home game.
Hopes of a double in Conte's first season in charge remain alive.
Both Kante's Chelsea goals have come against United, who have not beaten the Blues in 12 attempts, since October 2012.
Mourinho, whose side won the EFL Cup last month, had never lost a FA Cup quarter-final. He has now.
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Additional reporting by PA.