Harry saw ‘red mist’ in William’s face during dog bowl brawl

Prince Harry clearly doesn’t know the first rule of fight club.

The Duke of Sussex is going into yet more detail about getting battered by his brother, Prince William — saying he saw the “red mist” of anger in the heir apparent’s face during the heated confrontation.

In a new teaser for his interview with ITV News airing Sunday, Harry dishes about the brawl in which he claims William knocked him to the ground — and Harry valiantly refused to fight back.

It capped a period of mounting tension between the once-close brothers, which Harry blames on William’s hostility toward Meghan Markle.

“What was different here was this level of frustration,” he said of William as he allegedly burst into Nottingham Cottage, the Kensington Palace home Harry was living in at the time, just months before Megxit.

“I talk about the red mist that I had for so many years — and I saw this red mist in him,” Harry told ITV News’ Tom Bradby.

“He wanted me to hit him back, but I chose not to,” said Harry, heroically.

The distant duke also told the UK broadcaster that he called his brother his “archnemesis” because “there has always been this competition between us, weirdly.

“I think it plays into — or is played by — the ‘heir, spare,’” he said, of the comment that he accused their dad, King Charles III, of making the moment he was born.

However, he admitted in a separate interview with “Good Morning America” that the bitter feud he is making so very public would have broken the heart of their late mom, Princess Diana.

“I think she would be … I think she would be sad,” he admitted.

Still, she would side with him in seeing that there are things the brothers “need to go through to be able to heal the relationship.”

He also said his exit from the family made him feel closer than ever to his mom, who famously split from the current king amid ugly public allegations of cheating on both sides.

“I have felt the presence of my mom more so in the last two years than I have in the last 30,” Harry told ABC News of the time since quitting the UK and royal life.

Harry repeatedly justified his endless attacks on his family, coming from numerous sitdown interviews, his six-part Netflix docu-series and now his memoir, “Spare,” which is supposed to be under wraps until Tuesday but has been widely leaked after accidentally going on sale in Spain.

ITV’s Bradby reminded Harry that he has “railed against invasions of your privacy all your life, but … here are you invading the privacy of your most nearest and dearest without permission.”

Harry replied: “That would be the accusation from the people that don’t understand or don’t want to believe that my family have been briefing the press.”

Still, despite it all, Harry maintained that he still believes in the monarchy.

But asked if he would be playing a part in that, he conceded: “I don’t know.”