Toby Keith's July 6th Oklahoma Twister Relief Concert sold out in one hour last week. But that's not going to stop the country superstar from making the benefit bigger and better, and Carrie Underwood will definitely make this fundraiser for Oklahoma tornado victims bigger and better.

One of the reasons it took Underwood longer to agree to doing the relief benefit was a prior commitment at the Grand Ole Opry. But the Oklahoma native, Grammy Award winning American Idol will make her appearance and live performance via satellite from Nashville.

Carrie has been active in her support for the cause since day one. She has already make a $1 million contribution for tornado victims, and put on an unforgettable performance at this year's CMT Awards.

Underwood joins an all-star and legendary cast of musicians like Toby, Willie NelsonGarth BrooksTrisha YearwoodRonnie DunnSammy Hagar, Mel Tillis and John Anderson.

Will there be more star power added to the Oklahoma Twister Relief Benefit? We shall see.