Johnny Depp once sexually assaulted Amber Heard with a liquor bottle, the actress’ attorneys alleged in court Tuesday during the ex-couple’s bombshell defamation trial.

In opening statements, Heard’s lawyers detailed harrowing instances of abuse at the hands of the “Pirates of the Caribbean” star, including on a trip the then-married pair took to Australia in 2015.

After gobbling between eight and 10 ecstasy tablets, the actor allegedly ripped off Heard’s nightgown, dragged her across the floor, “told her he’s going to f—ing kill her, and he f—ing hates her” and punched and kicked her, Heard attorney Elaine Bredehoft said.

“Then he penetrates her with a liquor bottle — that’s the Johnny Depp you’re going to hear about in this case,” she told the jurors.

Depp, 58, is seeking $50 million in damages from Heard, 35, who he claims defamed him when she wrote in a 2018 Washington Post op-ed that she was a victim of “sexual violence.”

While Depp wasn’t named in the op-ed, the actor claims it ruined his reputation and career after it was widely assumed Heard was writing about their five-year relationship.

His attorney told the jurors they probably know Depp as a “respected artist whose name was linked with success at the box office, but: “Today his name is associated with a lie.”

“The evidence will show that Ms. Heard’s false allegations had a significant impact on Depp’s family and his ability to work in the profession he loved,” Benjamin Chew said in the Fairfax, Virginia courtroom.

“A false allegation can devastate a career and it can devastate a family,” Chew said.

Heard’s side agreed that Depp’s career is in shambles, but said his downfall was self-inflicted.

“Make no mistake, Johnny Depp’s reputation is in tatters. His career is in a free fall,” defense attorney Ben Rottenborn said in his opening. “But it’s because of problems that he created … It’s not Amber’s fault. It’s because of the choices he made.”

Her attorneys said they would show how Depp was an “obsessed ex-husband hellbent on revenge,” who engaged in “crushing drug and alcohol abuse.”

Heard, who wore a gray suit with a black shirt and her hair tied back, looked mostly stoic through the opening statement, even as Depp’s lawyers painted her as a lying and deceptive temptress.

“The evidence will show that Ms. Heard used allegations against Mr. Depp to raise her own profile and advance her career,” one of Depp’s attorneys, Camille Vasquez, told the court.

She claimed Heard’s allegations of domestic abuse were “designed to shock” “overwhelm” and “distract from the evidence” — and that the “Aquaman” actress wrote the op-ed as an attempt to “manipulate” the #MeToo movement.

Depp, who had walked into the courtroom with a big smile on his face, to gasps from onlookers, sat back in his chair, looking somber as his attorneys spoke.

He smirked or cringed during the opening statement from Heard’s legal team — which didn’t shy away from detailing her claims of violence and abuse.

In response to the sexual abuse accusation, a spokesperson for Depp said after the hearing: “These fictitious claims were never made at the onset of Amber’s allegations in 2016, and only advantageously surfaced years later once she was sued for defamation after noting in her op-ed that she was a victim of ‘sexual violence.’”

“Words are key in a defamation case and conveniently, this allegation only came after that,” the statement said.

More than a dozen fans — some from as far as Portugal and London — had lined up outside the courthouse before sunrise, including several who camped out overnight, in order to catch a glimpse of the Hollywood stars.

In the courtroom, some cried during the opening testimony from his lawyers.

Maryland massage therapist Tiffany Lynn, 39, told The Post she was hoping to spot Depp inside the courtroom, after only seeing him whisked off in a car Monday, when the panel of seven jurors and four alternates was selected.

“I feel what is going on with [Johnny] and his personal life being put out there, the truth will come out. He needs to get justice and be vindictive,” Lynn said.

Yvonne de Boer flew in from Los Angeles and said she was running high on “Johnny adrenaline.”

“I’m gonna be here for 31 days but gotta go back and forth to LA but will be here for the verdict. I believe him and I know he’s innocent and I want him to get his justice,” she told The Post.

Judge Penney Azcarate has already banned the A-list litigants from signing autographs or posing for pictures in or outside the courthouse in a bid to prevent the case from turning into a media circus.

Heard’s lawyers sought to have the case tried in California, where both actors live, but a judge ruled Depp was within his rights to bring the suit in Virginia because The Washington Post’s computer servers for its online edition are located in Fairfax County.

On Tuesday, Heard’s team argued that freedom of speech “is the central issue in this case.”

“Of those words that Amber wrote: are those protected by the First Amendment? And the answer is very clearly yes,” Rottenborn said.

Depp’s lawyers acknowledged the actor’s “real struggle” with substance abuse, including during his five-year relationship with Heard. But they said that while Depp is “not a perfect person,” he “does not abuse women.”

“You’ll learn that Johnny Depp is a kind soul who would never raise a hand on a woman,” Vasquez said.

She also claimed to the jurors that Heard would use her skills as an actress to try to manipulate them.

“She has been living and breathing this lie for years now, and she has been preparing to give the performance of her life in this trial,” Vasquez said.

The trial is expected to last more than a month and include testimony from both Heard and Depp and a string of other high-profile names, including Elon Musk and James Franco.

Depp’s older sister Christi Dembrowski was the first witness to be called to the stand, describing the Hollywood couple’s volatile relationship.

The pair, who were married in 2015 and divorced in 2017, fought often, Dembrowski told the jury, noting that her younger brother’s “standoffish” ex-wife would often deride him — and once called him an “old fat man.”

When asked about her reaction to their decision to wed, Dembrowski replied: “I was scared, I was devastated actually.”

She is set to continue her testimony on Wednesday.