Manchester United's manager Jose Mourinho (L) talks to Chelsea head coach Antonio Conte after the final whistle at Stamford Bridge in London on October 23, 2016Manchester United's manager Jose Mourinho (L) talks to Chelsea head coach Antonio Conte after the final whistle at Stamford Bridge in London on October 23, 2016 (AFP Photo/Ben Stansall)
Prior to walking down the tunnel following Sunday's game, stony-faced former Chelsea manager Mourinho cupped Conte's head and spent a good while whispering in the Italian's left ear.
Pitch-side microphones suggested Mourinho had accused Conte, in Italian, of trying to "humiliate" his side by urging the home fans to make more noise, but the United manager refused to go into detail.
"You know me. I spoke to Conte, not to you," Mourinho told his post-match press conference.
"I'm not the kind of guy to come here and share with you things I don't want to share.
"What is between me and Antonio is for us, or up to him to talk if he wants to. That is his problem. I have no comment."
Conte was also reluctant to discuss the matter, although he defended himself for whipping up the crowd after N'Golo Kante had waltzed through the United defence to score Chelsea's fourth goal.
"I think that, today, it was right to call our fans," he said.
"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. The players, after a 4-0 win, deserved a great clap.
"We live with emotions. If you want to cut the emotions, we can stay at home and I will change jobs."
Mourinho was returning to the scene of some of his greatest triumphs as a manager, but left after being consigned to his heaviest loss since Real Madrid's 5-0 humiliation by Barcelona in November 2010.
It took Chelsea just 30 seconds to go ahead, Pedro Rodriguez nipping in behind an inattentive Chris Smalling to score.
"We made an incredible defensive mistake -- I say incredible in capitals," said Mourinho.
- Luiz let-off -
Lax marking at a corner allowed Gary Cahill to lash home the hosts' second in the 21st minute.
Eden Hazard and Kante further inflated Chelsea's lead in the second half and Mourinho's misery was compounded by what he described as a "really bad" knee ligament injury to Eric Bailly.
Chelsea might also have lost a centre-back had referee Martin Atkinson taken a dimmer view of a knee-high foul on Marouane Fellaini by David Luiz shortly before half-time, for which he was booked.
The result left United five points behind fourth-place Chelsea and six points below leaders Manchester City in seventh place, but Mourinho tried to apply a positive gloss to his team's position.
"We are six points from the top of the league. We are not 16 points," he said.
"We are maybe three, maximum four, from the top four (actually five). We are not 30 or 40. So we are there.
"We are there with very difficult fixtures in a week where we've played away to two candidates (having previously drawn 0-0 at Liverpool).
"I'm not saying the matches coming up are easy. Far from it. But we have to beat opponents from mid-table that we are going to have now.
"Burnley, Swansea, Sunderland, Middlesbrough -- they're difficult, but we need points from these matches.
"The top teams play against each other so they have to lose points, so in the end we'll be around."
Chelsea have won three successive league games without conceding a goal since Conte switched to a 3-4-3 formation duration their 3-0 defeat at Arsenal.
"After this type of win, usually it increases your confidence," said Conte, whose side visit West Ham United in the League Cup in mid-week.
"You trust more in the work you're doing. That's the most important thing.
"But we must continue. The United victory is the past. We must concentrate on Wednesday and another tough game against West Ham."