Zlatan Ibrahimovic has described Pep Guardiola as "immature" over the way the Manchester City boss managed him during their spell together at Barcelona.
The Manchester United striker moved to the Nou Camp from Inter Milan in the summer of 2009 but endured a turbulent year in Catalonia and fell out with Guardiola, whom he blamed for a lack of first team opportunities.
Ibrahimovic started 23 of his 29 appearances in all competitions and netted 16 goals but later, in his book I Am Zlatan, accused Guardiola of being a "spineless coward" and explained the pair fell out during their time together as the current City manager opted to build his side around Lionel Messi.
The 36-year-old has now reopened the rift with Guardiola during an interview with Sky Italy.
"The first six months were perfect, then the manager changed system, tactics and it didn't work for me," Ibrahimovic said, the Daily Telegraph report.
"I went to talk to him. I'm here to talk, if you think it's for another reason then we can't talk.
"I said: 'I believe that you are sacrificing some players for one player, Messi'. He said: 'I don't think this is the case but I understand what you say. I will take care of it, no problem, I will solve everything'. I thought it would be OK."
However, the situation did not improve at all and the former Sweden captain feels Guardiola deliberately ignored his efforts.
"The following game I was on the bench. I don't say anything, I work," he added. "Second match bench again. I thought he solved it well and he was not talking to me or explaining. Third match bench. Then the fourth match comes and bench again.
"I think something is strange. From that moment he stopped talking to me, looking at me. I go into a room and he walks out of it. He was not a bad person, but the most immature I've had because a man solves his problems."
Ibrahimovic was a second half substitute in United's 2-1 defeat against their local rivals on Sunday (10 December), which saw them fall 11 points behind league leaders City – who also brought United's 40-match unbeaten run at Old Trafford to an end.
The result, however, was overshadowed by a fracas involving players from both sides, which is said to have been prompted by City's celebrations and music from inside the away dressing room.
Jose Mourinho is said to have tried to enter the dressing room to object, clashing with City goalkeeper Ederson before a 30-man melee ensued, with the FA now investigating the incident.