Jelly Roll encouraged the remaining 42 singers as they paired up for "Idol's" head-to-head round. He also brought in special guest Brandon Lake.

These include famous duos like Sonny & Cher ... to collaborate and cowrote many of Lennon's most famous songs, including "Give Peace a Chance" and "Imagine." Their last album together, 1980's ...

Sonny Tennet can now count Lionel Richie ... U.K.-based singer-songwriter took a big chance by performing one of Richie’s songs for his audition. Tennet, 25, told Richie, along with judges ...