British pop star Ed Sheeran sang and played the guitar on the witness stand Thursday, giving jurors a fleeting free concert during his copyright infringement trial in New York, US media reported.

Sheeran played the basic four-chord progression of his Grammy-winning song, Thinking Out Loud, denying that it is a copy of Marvin Gaye’s 1973 soul classic Let’s Get It On, the New York Times said. 

The English musician also sang what he said were his song’s original lyrics, “I’m singing out now,” ABC News reported.

The lawsuit against Sheeran was filed by heirs of Gaye cowriter Ed Townsend, who allege that harmonic progressions and rhythmic elements of his 2014 song were lifted from the classic made famous by Gaye without permission.

The heirs are seeking a share of the profits from Sheeran’s song.

Sheeran said he writes most of his songs in a day, and noted that he cowrote Thinking Out Loud with singer-songwriter Amy Wadge, a regular partner.

Marvin Gaye. Photo: Wikipedia

The two wrote Thinking Out Loud at Sheeran’s home in February 2014, he said.

“We sat guitar to guitar,” Sheeran said, according to ABC News. “We wrote together quite a lot.”

Both Wadge and he had suffered recent loss, Sheeran said, noting that his grandfather had just passed away and his grandmother was battling cancer. Wadge had family members who were fighting illness.

They wanted to pay tribute to those around them that they loved, he said.

Sheeran said he was coming out of the shower when he heard Wadge strumming some chords in another part of the house.

“I remember thinking, ‘We have to do something with that’,” he told the court, ABC News said.

The jurors must decide if Sheeran’s song and Gaye’s classic are substantially similar and if their common elements are protected by copyright law.

A musicologist serving as a witness for the Townsend heirs testified that the Sheeran’s and Gaye’s songs use a nearly identical four-chord progression –prompting Sheeran to reach for his guitar, the New York Times said.

Sheeran played both the second major chord, which he said he’d played in every public performance, then a second minor chord used in Let’s Get It On. He said it worked well for Gaye but not for his song, the Times reported.

The trial resumes on Monday, when Sheeran is expected to testify further – with or without guitar.