Hulk Hogan was "completely humiliated" after a secretly-recorded s3x tape was published on a gossip website, a court heard on Monday.
The wrestling star is seeking $100million (£70million) in damages from Gawker, who leaked the footage of his romp with the wife of his then-best friend, radio shock jock Bubba the Love Sponge.
The court case will test celebrity privacy rights and freedom of the press in the digital age.
Hogan, 62, said the publication of the one-minute, 41-second clip of his consensual s3x with Heather Clem deeply affected his personal and professional life.
"I was completely humiliated," he said. "It was even embarrassing as my character. Hulk Hogan was embarrassed."
Addressed in court by his legal name, Terry Bollea, the wrestler wore a signature bandana with a black suit and a cross necklace.
He referred to his Hulk Hogan character as "completely opposite" to his true personality, which he described as soft-spoken and non-argumentative.
Lawyers for the longtime WWE champion and reality TV star say he had a right to expect privacy in a private bedroom and the video was filmed without his knowledge.
Gawker's post was motivated by power and brand promotion, an attorney for the wrestler told jurors during opening statements.
Gawker attorneys, however, questioned what the wrestler knew about cameras in his friend's house.
Gawker sees its 2012 post as protected speech under the First Amendment of the US Constitution, and contends it was reporting on a celebrity who publicly discussed his s3x life.
Gawker's founder, Nick Denton, sat in the front row on the first day of a civil trial in St. Petersburg.
"Gawker believes this kind of reporting is important," an attorney for the company, Mike Berry told jurors, explaining that celebrity s3x tapes are among the "uncomfortable" topics important to the outlet, known for gossip and media reporting.
A loss could put Gawker out of business, though the website will appeal an unfavorable verdict, another of its attorneys said.
The wrestler said the incident occurred at a low-point as his marriage was ending, in a home where he had let down his guard.