Fan sings with Cynthia Erivo during concert at the Mann Center in Philadelphia's Fairmount Park

PHILADELPHIA (WPVI) -- An incredible moment unfolded at the Mann Center in Fairmount Park over the weekend.

Concertgoers at Cynthia Erivo's performance with the Philadelphia Orchestra went home wondering about the woman who joined the "Wicked" star for an impromptu duet.

Cynthia Erivo was walking throughout the crowd, singing Aretha Franklin's "A Natural Woman," when she found herself singing with a mystery audience member.

That talented woman was Marielle Alcantara, a native of the Philippines and South Philadelphia resident.

She was at the concert alone, and started rolling on the duet when Erivo walked over and started singing with her.

Erivo shared that video on Instagram writing, "Sometimes it's YOUR singing that makes ME happy!! Thank you Philly!"

She didn't tag Marielle in the video, so we asked the internet to help us find her.

Boy, did they come through!

Marielle answered our one big question: was she planted there?

Her answer: no!

"I think I was in a lucky seat," she says, excitedly. "When Cynthia walked down the stairs, we immediately locked eyes, and I was kind of mouthing to her: 'Can I sing with you?' And she went over to me, and she shared her mic with me, and that's when the magic happened!"

No surprise to anyone in the crowd who heard the duet, Marielle LOVES to sing.

"I sing in a Filipino church choir at St. Augustine in Old City," she says. "I also go to a piano bar, shoutout to Tavern on Camac! That's where I usually go to to sing show tunes and everything."

Cynthia Erivo clearly learned that not only is Philly prepared, but give us the mic and we WILL sing!