I love when Idols from different seasons collide, and it happened in a big way at Sunday’s Daughtry concert in Nashville.

Kelly Clarkson joined Chris Daughtry on stage for an acoustic version of Tracy Chapman’s “Fast Car.” Chris introduced it as “one of my favorite songs, that I wish I had written.”

Joining Daughtry during the encore were Three Doors Down frontman Brad Arnold for a cover of the Allman Brothers’ “Whipping Post, ” and Jason Wade, the frontman for support act Lifehouse, performing on the band’s song “Home.”

The special guests helped Daughtry turn the regularly scheduled tour stop into a flood-relief benefit, offering tickets in several sections of the Bridgestone Arena for $10 each.

Brian Mansfield of Idol Chatter was there, read his re-cap of the concert HERE.

Watch Chris and Kelly sing “Fast Car” after the jump. Very awesome!