Ed Sheeran sings ‘Thinking Out Loud’ during Marvin Gaye copyright trial

He was singing out loud.

Ed Sheeran performed a snippet of “Thinking Out Loud” in front of a Manhattan courtroom Thursday, singing and strumming a few notes on an acoustic guitar during his Marvin Gaye copyright infringement trial.

While testifying on the witness stand, the “Shape of You” singer took a tan Lowden wooden acoustic guitar and played the basic four-chord progression highlighting the 2014 hit single, giving the courtroom an intimate teaser of his gigs.

Sheeran’s appearance came after his attorney Ilene Farkas called him to the stand to refute comments made by the plaintiffs’ musicologist Alexander Stewart, who argued that the first 24 seconds of “Thinking Out Loud” were similar to the beginning of Gaye’s “Let’s Get it On.”

However, Sheeran said that Stewart’s analysis was wrong, and performed the version he said he plays at every concert before he then played Stewart’s version.

“It works very well with him, but it’s not the truth,” Sheeran said.

The 32-year-old British singer-songwriter explained the origins of “Thinking Out Loud” and how the song was created after the death of his grandfather and watching his grandmother’s health decline.

The song, which was written with longtime collaborator Amy Wadge, came to life after Sheeran hopped out of the shower of his home and heard Wadge strumming the chords.

Kathryn Townsend Griffin — the daughter of the late Ed Townsend, who co-wrote the 1973 R&B classic with Gaye — wasn’t present Thursday.

She had collapsed in court Wednesday and left the Moynihan Courthouse on a stretcher.

Her attorney Ben Crump said that she was feeling better and is expected to return to court next week.

Judge Louis L. Stanton threatened to boot Crump for not following instructions after presenting emails from Sheeran’s manager Stuart Camp that weren’t submitted to evidence.

“Do you remember when I told you not to testify,” Stanton said.

“It wasn’t very long ago, about five minutes ago.

“… If you don’t follow my instructions, I will disqualify you.”

Sheeran, who signed a fan’s book during a court break earlier in the day, is scheduled to resume testifying on Monday.