Ed Sheeran says he'd never heard Marvin Gaye's 'Let's Get It On' until he watched 'Austin Powers' amid accusations he copied the track on 'Thinking Out Loud'

• Ed Sheeran took to the stand for the first time in his "Thinking Out Loud" copyright trial on Tuesday.
• The singer is being sued by the heirs of the cowriter of Marvin Gaye's "Let's Get It On."
• Sheeran told the court he hadn't heard Gaye's song until he watched the 1999 movie, "Austin Powers: The Spy Who Shagged Me."

Ed Sheeran claimed he hadn't heard Marvin Gaye's "Let's Get It On" until he watched "Austin Powers" as he took to the stand for the first time in his "Thinking Out Loud" copyright trial.

The heirs of Ed Townsend, who cowrote "Let's Get It On," are suing Sheeran, alleging that his 2014 song "Thinking Out Loud" has "striking similarities" to Gaye's 1973 soul classic.

Townsend's heirs claim that Warner Music Group and Sony Music Publishing owe them money for stealing elements of the song.

Appearing in a Manhattan federal courtroom on Tuesday, Sheeran testified that he did not copy from Gaye's song.

"It is my belief that most pop songs are built on building blocks that have been freely available for hundreds of years," the 32-year-old singer told the court, according to People, before pointing out that a number of other popular songs, including Van Morrison's "Crazy Love" and "Someone You Loved" by Lewis Capaldi, share the same progressions.

Sheeran later said, according to People, that he first heard "Let's Get It On" in the 1999 movie "Austin Powers: The Spy Who Shagged Me."

He insisted, however, that "Thinking Out Loud" was not based on Gaye's song, but instead on a conversation that he and cowriter Amy Wadge had about his grandparents.

The song is about finding love at an old age, he told the court, according to NBC News.

Listen to "Thinking Out Loud" here:

And "Let's Get It On" here:

Earlier on Tuesday, Sheeran was questioned about a live mashup of "Thinking Out Loud" and "Let's Get It On" he performed during a 2014 show in Zurich, which was caught on camera.

Ben Crump, a lawyer for the Townsend family, told the court that the concert video amounted to a "smoking gun" confession, according to the BBC.

Sheeran responded by saying that he often mixes songs with similar chords at his performances.

"You could go from 'Let it Be' to 'No Woman, No Cry' and switch back," Sheeran said, referring to the classic songs by The Beatles and Bob Marley.

"If I had done what you're accusing me of doing, I'd be quite an idiot to stand on a stage in front of 20,000 people and do that," he added, according to People.

Sheeran is expected to testify once more as the trial, which is set to last for around two weeks, proceeds.