Blake Shelton admits he was nervous when Season 4 of NBC's "The Voice" was getting a face lift after Cee Lo Greene and Christina Aguilera took time off to from the show to fulfill their busy schedules. Cee Lo Greene will be back for Season 5 of singing competition, it's unclear who will leave the show as of now to make room for the original judge/mentor. Shelton was nervous about the camaraderie between all the coaches because things worked so well before and he had never met new comers Usher and Shakira, but Shelton's wife, Miranda Lambert gave him a crash course on just how big of stars Usher and Shakira really are.