Jose Mourinho has hit out at Everton manager Ronald Koeman for his public pursuit of Manchester United forward Memphis Depay.
Koeman has confirmed his interest in signing Depay, who has struggled to make an impact since arriving from Dutch giants PSV in June last year.
The 22-year-old has only made four substitute appearances in the Premier League this season, though he scored a brace in Netherlands' 3-1 World Cup qualifying win over Luxembourg.
But United boss Mourinho has been left angered by Koeman's comments about Depay in the media.
"I think that my normal answer if somebody asks me about a player from another team, my normal answer is 'the player is not my player, the player belongs to another team, the player belongs to another manager', no comments at all," Mourinho said.
"I think that is the ethical answer and when we are always worried about ethics and respect, and rules, I just said that if it was me making that kind of comment about an Everton player, I would be in trouble."
Mourinho and United play host to Arsenal in the Premier League on Saturday.