Sammy Hagar has been added to the growing all-star lineup of Toby Keith's Oklahoma Twister Relief Concert, scheduled for July 6.

The event, which will take place at the University of Oklahoma's Gaylord Family-Oklahoma Memorial Stadium in Norman, Okla., will also include appearances by Garth Brooks, Trisha Yearwood, Willie Nelson, Ronnie Dunn and Keith, who hails from Moore, a town that lost 24 residents when a series of deadly tornadoes hit the state on May 20.

Tickets, set at $25, will go on sale tomorrow (June 21). Proceeds are being earmarked to benefit the United Way of Central Oklahoma's tornado-relief efforts.

Hagar, currently making his way through the Four Decades of Rock tour, has been friendly with Keith for years. He covered the country star's 'I Love This Bar' on his 2006 album 'Livin' It Up!,' and the pair later recorded a Christmas duet, 'Santa's Goin' South.' Keith has been known to appear with Hagar at various live performances, so the Twister Relief audience shouldn't be surprised to see a guest appearance or two during their sets.

The Twister Relief show falls in the middle of a busy year for the Red Rocker, who's celebrating his 40-year career milestone while laying down tracks for his next record, which will reportedly include a cover of Depeche Mode's 'Personal Jesus' as well as appearances by Neal Schon of Journey and Hagar's surviving Montrose bandmates.