Manchester United boss Jose Mourinho has revealed the red card received by Marouane Fellaini for clashing with Sergio Aguero still rankles with him.
Fellaini was given his marching orders during a derby match with City 18 months ago, after appearing to strike Aguero in the face.
The Argentine went down theatrically, convincing referee Martin Atkinson to show Fellaini a red.
Mourinho had reacted angrily after that match, telling reporters: "If Sergio doesn't go to the floor for sure it's not a red card."
And it appears that the intervening year and a half has done little to calm the manager's indignation.
"There are little things in his game that I am not a big fan. I keep (the reasons) for me," Mourinho said of City's centre-forward ahead of Sunday's derby at the Etihad Stadium.
"I admire him because of his fantastic qualities. Clearly the numbers speak for themselves. He is a goalscorer all over the world. It is not about scoring for one season, it is about scoring goals in your career.
"Martin Atkinson told me in his opinion it's a red card but I saw Aguero in the tunnel but no broken head, no broken nose, his face is nice as always."
City welcome their Manchester rivals to the Etihad as sole leaders of the Premier League, having picked up 29 points of an available 33 during a dominant start to their title defence.
United, meanwhile, have not been at their best so far, sitting eighth in the standings with just six wins in 11 outings.