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

chris daughtry and kelly clarkson perform "fast car" - YouTube

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.”

Chris Daughtry & Kelly Clarkson - "Fast Car" Nashville, TN

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.

'Idol' Duet -- Daughtry & Kelly Clarkson!

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