BEVERLY HILLS, CA - FEBRUARY 12: Singers Monica (L) and Brandy arrives at the 2011 Pre-GRAMMY Gala and Salute To Industry Icons Honoring David Geffen at Beverly Hilton on February 12, 2011 in Beverly Hills, California. (Photo by Jason Merritt/Getty Images)

Monica opened up about how tricky it is for her to perform her fan-favorite 90s song without the help of Brandy.

Find out why she thinks nobody can do Brandy’s part justice.