Ronny Deila watched Inter Milan beat Palermo 3-0 as a new row kicked off in the San Siro.
The win brought an end to a three match losing streak but striker Mauro Icardi found little to celebrate.
The Argentinian striker scored twice but barely celebrated or acknowledged either goal after having his jersey thrown back at him after handing it over to fans at the end of last week’s defeat from Sassuolo.
“In my opinion you should celebrate after a goal,” Roberto Mancini told Sky Sport Italia. “I don’t think he’s unhappy, I assume it’s a leftover from last Sunday. The fans cheered him so it seems to be sorted out.
“(Fredy, who opened the scoring) Guarin played well, though at times he gets a bit stubborn with the ball and can lose his way.
“He’s perfect as the deeper point of a midfield three, as he plays the ball well and has great power.”
The win lifted Inter ahead of city rivals Milan into 11th place in the table with both sides sitting on 29 points from 22 matches.
On Sunday Inter make the short journey to Atalanta before heading to Glasgow and their eagerly awaited Europa League tie with Celtic.
Deila flew out to Milan following Celtic’s 2-0 win at Dundee and is eagerly looking forward to the resumption of the Europa League.
“I’m really looking forward to those matches against Inter now,” the Celtic boss said.
“I’m much more confident now in that we’re together and know how we want to play the game. We’ll have a big test against them but it’s something I’m excited about.
“The team who is developing the most will win the tie. And my teams develop all the time, we never stop.
“We just go on and on and we’re working hard every day to get the small things right. We’ll see how far we’ve come when we face Inter.”