Led Zeppelin guitarist Jimmy Page has told a court he had not heard a song he is accused of copying when he wrote Stairway To Heaven, until his son-in-law played it for him on the internet.
The British musician said the instrumental track Taurus, by American band Spirit, was "alien" to him and he was "confused" about why it was being linked to his classic 1971 hit.
A lawsuit has been filed by Michael Skidmore, the trustee of Spirit guitarist Randy Wolfe - known as Randy California - who drowned in 1997 having never taken legal action over the song.
Jimmy, 72, told the federal court in Los Angeles that he "liked" Spirit in the late 1960s but he only became aware of the song Taurus in recent years.
"It was after the internet comparison which came up a few years ago," he said.
"My son-in-law brought to my attention a comparison of Stairway To Heaven and a Spirit song. I said I'd like to hear it. I don't do the internet or computers so he played it to me."
Jimmy said the music by Spirit began with an orchestra which was "totally alien" to him.
"I knew I had never heard it before," he told the court. "Something like that would have stuck in my mind. I would remember that.
"I was a bit confused because I thought, 'What has this got to do with Stairway To Heaven?'."
Page was joined in court by Led Zeppelin singer Robert Plant as both men face a copyright infringement trial over the opening guitar riff of Stairway To Heaven.
Giving evidence on the second day of the trial, Page said he was aware of "some of sort of buzz" on the internet about a comparison between Stairway To Heaven and Taurus and acknowledged both tracks were in the same key of A minor.
He told the court he had never seen Spirit play live, despite them performing on the same bill when Led Zeppelin played their first US concert in Denver, Colorado, in December 1968.
"I always thought the Denver show was us supporting Vanilla Fudge," he told the court.
The veteran rocker said he could remember owning Spirit's second and third albums in the 1960s but only discovered later that he possessed their first and fourth albums and a live recording by the band.
He told the court he owned a "massive amount" of music and a recent count had revealed he had 4,329 albums and 5,882 CDs.
The court heard that Led Zeppelin would play a riff from Spirit's song Fresh Garbage during a medley in their early shows in the late 1960s.
The Whole Lotta Love musicians would "wink to music that was hot at the time", Page said in written evidence read to the court.
-- Led Zeppelin (@ledzeppelin) July 27, 2015
"We didn't have a lot of material in those days," he added.
Jimmy, wearing a black three-piece suit, with his grey hair tied back in a ponytail, nodded his head to the music as Fresh Garbage was played to the jury during the hearing.
Earlier, Wolfe's former bandmate Mark Andes told the court that Spirit played Taurus at the Denver concert.
-- Led Zeppelin (@ledzeppelin) June 8, 2015
He said Spirit also played at music festivals in Texas, Atlanta, North California and Seattle where Led Zeppelin were on the bill.
The court was shown videos of Stairway To Heaven and Taurus being performed on an acoustic guitar.
Mr Skidmore's lawyer Francis Malofiy asked: "Do they sound the same to you?"
Mr Andes replied: "They do."
The musician told the court that members of Spirit played snooker with Plant after the US group played a gig at Mothers club in Birmingham in 1970.
The trial was adjourned until Thursday.