Peter Cetera 's tenor voice complimented the baritones of his bandmates Robert Lamm and Terry Kath .
Cetera shared lead vocal on three of the eleven songs on the album , with his tenor voice complementing the baritone voices of the two other lead singers in the group ( keyboardist Robert Lamm and guitarist Terry Kath ) .The follow-up album , Chicago , vaulted the band to popular status throughout the world .
Peter Cetera