SPOILER ALERT: Casey Abrams sings Nirvana tonight! Plus, Thia Megia spoiler!

As reported on mjsbigblog today, Casey Abrams will sing “Smells Like Teen Spirit” Wednesday night on "American Idol," according to Nigel Lythgoe, from an interview on Ryan Seacrest’s KIIS radio show this morning: 

For the first time in ‘Idol’ history, a contestant will sing a Nirvana song on tonight’s                 performance episode themed around songs from the Top 12's birth year. Following a hospital stay that kept him from last week’s results show, Casey Abrams, who was born in 1991, will sing “Smells Like Teen Spirit.”

Also, Thia Megia will sing the theme from “Pocahontas," “Colors of the Wind.”

Melissa Etheridge tweeted yesterday that one of her songs would be performed tonight.