A Boston street performer sang ‘All of Me.’ Then John Legend showed up.

“It was a nerve-wracking moment, but it was something I enjoyed tremendously,” said singer Radha Rao.

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Radha Rao covers John Legend’s hit single “All of Me” at almost every set she plays in Boston. But never did she expect the Grammy-winning artist himself to show up at one of her performances.

In a clip posted on social media Sunday, Legend, clad in a tan trench coat, is seen walking up to Rao, giving her a tip and hugging the street musician after her performance outside Boston's historic Faneuil Hall Marketplace.

"I started singing the song and I was enjoying myself, and I see this man wearing a trench coat and a mask and I think, 'That looks a lot like John Legend — why would he be in Boston?'" Rao, whose stage name is Radha, told NBC News. "When he took off his mask, I was shocked."

“I just kept singing," she continued. "It was a nerve-wracking moment, but it was something I enjoyed tremendously."

A large crowd encircling Rao cheered as the 22-year-old singer and Legend embraced, the video showed.

Legend, 42, was in Boston with his wife, Chrissy Teigen, and his two children, Luna and Miles — all of whom could be seen watching from afar, Rao said.

After the performance, Rao said Legend shared a few words of gratitude: "Thank you so much for singing my song."

She continued: "He was so incredibly humble and encouraging to local artists. I look up to him immensely, and I love that he plays acoustic instruments like I do."

As for the future, Rao said she plans to continue balancing street performing and working her full-time job at a music technology company — all while pursuing her dreams to become a full-time artist.

"I personally love R&B, jazz, hip hop, and I like to interweave my Indian melodic training into my music," she added. "I want to continue cultivating strong relationships through my live performances, and I want to continue making my own music."