Jose Mourinho was in buoyant mood after Man United claimed a dramatic 2-1 comeback win away to Juventus - but one player took exception to the Red Devils manager's exuberant post-match celebration.
ourinho has been under pressure this season after a slow start in both the Premier League and the Champions League, but his players showed great spirit to overturn a 1-0 deficit through a Juan Mata free kick and a Sandro own goal in the final four minutes.
Juventus star Leonardo Bonucci, who assisted Cristiano Ronaldo's glorious volleyed opener, was clearly unhappy with his side's capitulation - and was even more unhappy after Jose Mourinho's passionate pitch invasion.
Mourinho cupped his ears towards the stand as he hit back at his critics, before exchanging words in a heated exchange with the Juventus defender.
United could scarcely have wished for better preparation for Sunday's derby clash at swashbuckling Manchester City as the headlines were snatched away from Ronaldo.
Sami Khedira and Paulo Dybala hit the woodwork either side of half-time despite United's improved display, which looked like it would be undone by their former hero meeting a Leonardo Bonucci clipped pass with an astonishing volley.
Juventus threatened more goals but United dug deep and produced another memorable victory in Turin.
Mata came off the bench to equalise with a superb free-kick in the 86th minute and another set piece would produce a last-gasp winner, with Ashley Young's free-kick eventually going in off Sandro and sending the visitors wild.
Mourinho certainly lapped up the moment at the Allianz Stadium. A fortnight on from responding to inflammatory chants from the Juventus fans at Old Trafford by holding up three fingers, representing the treble he oversaw when manager at Inter Milan, he took to the pitch and cupped his ear at full-time.
"Well, do you remember what they did to me? Well, the sign I made is actually not an offence," Mourinho said.
"This is something more... I just wanted to hear them making comments again or not. Yes, before I said I would not do it but then I did (react)."
You can see why Mourinho got caught up in things on a night where he praised substitute Marouane Fellaini for making "the team alive again".
The imposing midfielder made his presence felt as the winner went in, with victory injecting new life into their Champions League campaign and providing a great lift ahead of Sunday's derby clash at Manchester City.
"I think we played this season against Chelsea and Juventus away, the two best teams that we faced this season, and we played very well in both," Mourinho said. "Very well in both.
"In here, lucky to win in the last minute. Against Chelsea, unlucky not to win in last minute, but we played very, very well and this is what we want.
"We want to play well, we want to go to every stadium and it doesn't matter the team and we play.
"Then, if they are better than us, they win. If they have more potential than us, they win. If we make mistakes and pay for the mistakes, we lose.
"But I want the feeling that it doesn't matter where we go, we go to compete and I think this is a feeling that also the Manchester United supporters around the world want to have - switch on the television and it doesn't matter where we play, they know we are going to compete.
"We will lose matches. Today we could lose, but that feeling of 'we go to play, we go to try to win'."
Juventus counterpart Massimiliano Allegri was naturally disappointed after falling to a late defeat on home turf.
"It's a shame," he said. "The team produced a good performance but were never able to put them to bed.
"There's always a risk when you play against the top teams. We give away too many free-kicks in both wide and central areas.
"That said, we're still top. We have two games left that we can use to ensure we win the group and go through to the last 16."