John Legend was stunned when he stopped during a busker's set and listened to her performing one of his hit songs. Watch below:
In footage shared on social media, the 22-year-old can be seen sitting at a piano and blasting out the tune.
At first, she didn't even know Legend was there because he was wearing a face covering, and it was only when he took it off that she spotted him standing right in front of her.
And Legend was so impressed by her voice that he even went over and left her a tip, as well as giving her a big old hug.
Speaking to Sky News, Rao said she was stunned to see the singer stop by and listen to the song, which is a regular number on her two-hour set.
She said: "It was something I didn't expect at all but it was a wonderful surprise to have. It's not common that you happen to be singing an idol's song and he's there. It was a special experience.
"I am a big fan and he is a big inspiration. I am going to always continue to sing that song.
"It's a fan favourite and one of my favourites.
"That memory will continue to help me perform."
She told ITV that she couldn't believe what was going on.
She said: "A lot of people tend to ask, 'Did you play it because he was there?' And the answer is no.
"I was playing it, and then he happened to appear after I started the song, so it was quite a shocking experience."
Speaking to NBC about the encounter, Rao said Legend was really sweet and that she won't ever forget it.
She said: "Obviously, it is not normal that you serendipitously happen to sing the songs that the true artist is there for. It was a bizarre experience.
"And I'm just nothing but grateful for his humility and his willingness to encourage local talent.
"I just wanted to make the most of the moment."