The Problem singer made her Broadway debut in the Tony winner's short-lived musical 13 in 2008, when she played a popular high school cheerleader in an all-teenage cast.

On Monday, Brown reunited with Grande during his gig at the Catalina Bar & Grill in Hollywood, and told the crowd, "Over the years, I've had the pleasure of working with so many great people, some of those kids turned out to be international pop stars, which was weird...

"I happened to bump into an international pop star the other day and I asked her if it would be fun to sing a tune or two and she said, 'Three,' and I said, 'Three would be fine.'"

Grande then took the stage to reprise a song from 13 called The Lamest Place In the World, and also covered one of Brown's own songs, Getting Out.

She later returned for the finale to join scheduled guest and Broadway veteran Shoshana Bean for a duet of Brand New You, also from 13.