Ryan Giggs head-butted his former partner after subjecting her to a "litany" of physical and psychological abuse over three years, a court has heard.
The former Manchester United and Wales footballer, 48, "entirely lost his self-control" and attacked his then partner, Kate Greville, and elbowed her sister in the jaw during an argument about his alleged infidelity, jurors were told.
The fight at their home in Worsley, Greater Manchester, followed three years of "systematic and at times violent abuse" of Greville, 36, by the retired footballer, the jury heard.
The trial at Manchester Minshull Street crown court heard details of expletive-laden and threatening messages Giggs sent his former partner. One email, after Greville had blocked Giggs on social media, read: "Please unblock me. All this blocking malarkey is poo. Promise no more naked piccies."
Another email accused Greville of telling "LIES LIES LIES" and said: "Only an evil horrible cunt does that. Absolutely astonishing. Now I look an utter twat after telling three of my friends I'm going to Scotland at the weekend." Giggs added: "I'm so fucking mad now I'm scaring myself because I could do anything."
Giggs denies charges of using controlling and coercive behaviour against Greville between August 2017 and November 2020.
He is also charged with assaulting Greville, causing her actual bodily harm, and of the common assault of her younger sister, Emma Greville, at their home in Worsley on 1 November 2020. He has pleaded not guilty to all charges.
Peter Wright QC, prosecuting, told jurors that while Giggs was "idolised" by his supporters on the pitch, behind closed doors there was a "much uglier and more sinister side to his character", adding: "This, we say, was a private life that involved a litany of abuse, both physical and psychological, of a woman who he professed to love."
Wright told the jury that Greville and Giggs had a "toxic" relationship and argued often about affairs the former midfielder was allegedly having.
Giggs would respond with "false displays of indignation" and would "gaslight" Greville into doubting herself, the court was told. Wright told jurors that the defendant would threaten to send images of her, "of a personal nature", to her friends unless she did what he said.
He physically threw her, and her belongings, out of an address they were staying at after Greville challenged him about another woman, and threw an item at her in a bust-up in a hotel room in London, the jury heard.
Their relationship culminated in a "heated" confrontation at their home on 1 November 2020 when Giggs "deliberately head-butted" Kate Greville, the jury was told. He allegedly elbowed Greville's sister, Emma Greville, in the jaw when she tried to stop the pair from "grappling together down on the floor".
Giggs's barrister, Chris Daw QC, said Giggs "fully accepts that his behaviour, on a moral level, was far from perfect" and that he "didn't always handle their arguments in the best possible way".
However, he added, the defendant denies coercive and controlling behaviour or physically assaulting Greville and her sister. The allegations, he said, were based on "distortion, exaggeration and lies".
Daw told jurors they might think Giggs and Greville behaved "like squabbling children, or teenagers, at best" and likened their romance to other "dysfunctional relationships that are destined to fail".
The trial, before Judge Hilary Manley, is estimated to last two weeks.
