Prince Harry opens up about his relationship with his brother Prince William in his tell-all new memoir Spare, which is set to be released Jan. 10.

In a clip from an interview with “Good Morning America” anchor Michael Strahan, which is set to air in full on Monday, he mentions that Harry refers to his brother as his “arch-nemesis” in the book.

Strahan shares, “There’s a quote in this book where you refer to your brother as your ‘beloved brother and arch-nemesis.’ Strong words. What did you mean by that?”

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Harry responds, “There has always been this competition between us, weirdly. I think it plays into or always played by the ‘heir/spare.'”

Elsewhere in the interview, he insists: “Ultimately, I don’t think that we can ever have peace with my family unless the truth is out there.”

Harry also claims William physically attacked him in 2019 in his book, according to an excerpt published by The Guardian.

Harry claims the argument took place after William called Meghan “difficult,” “rude” and “abrasive,” something Harry called a “parrot[ing of] the press narrative” about his wife.

Harry claims he tried to calm his brother down during the confrontation and offered him a glass of water.

“Willy, I can’t speak to you when you’re like this,” Harry writes, according to The Guardian.

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The excerpt continues, “He set down the water, called me another name, then came at me. It all happened so fast. So very fast. He grabbed me by the collar, ripping my necklace, and he knocked me to the floor. I landed on the dog’s bowl, which cracked under my back, the pieces cutting into me. I lay there for a moment, dazed, then got to my feet and told him to get out.”