On Saturday at the Red Rocks, the Allman Brothers Band and RatDog closed out their summer tour. One interesting collaborative endeavor crossed both band’s sets. RatDog opened up with a move from ‘Help On The Way’ Into ‘Slipknot’ but rather than segue into the customary ‘Franklin’s Tower,’ the group took the music into ‘Loser,’ with Derek Trucks adding guitar. Later in the evening, towards the end of the Allmans’ set, the song cycle was completed as RatDog’s Bob Weir, Jeff Chimenti, Mark Karan, Kenny Brooks and Jay Lane joined the ABB for ‘Franklin’s’ (Weir and Oteil Burbridge traded off lead vocals). Meanwhile, Susan Tedeschi was on hand and guested with both groups, joining RatDog for ‘A Hard Rain’s A-Gonna Fall,’ and the Brothers for ‘I Ain’t Superstitious’ and ‘Don’t Think Twice, It’s All Right.’ In addition, Warren Haynes appeared with RatDog during ‘Bird Song,’ ‘Loose Lucy’ and ‘Bertha.’