Now that Cee Lo Green and Christina Aguilera are exiting The Voice for a season and Usher and Shakira are coming on, remaining coaches Adam Levine and Blake Shelton have to come up with new strategies for persuading contestants to join their teams.  But according to Adam, Usher has a huge advantage in that department, and his name is Justin Bieber.

Rolling Stone reports that at a press conference promoting the new season of The Voice, Adam said that the fact that Usher recognized Justin Bieber's talent early on and mentored him to stardom is a powerful argument for why a contestant would choose him over any other coach.

"As much as I hate to say this about another coach in the beginning, Usher has done what this show has yet to do," Adam said. "[He's] launched a superstar, and that's our goal. That's the show's goal. That's something we want to do as an institution."

Usher himself points out that his entire career has prepared him to mentor emerging talent.  Rolling Stone reports that he said, "The one thing that I hope is to come into this show and be able to score an incredible entertainer that people will talk about for years and years and track it back. I am kind of a living example of that. I started on Star Search, and my career kind of launched from there."

OK, so what does Shakira, who's expecting her first child, bring to the table as a coach?  "She plays the female card quite a bit," Adam said. "That's one thing we can't compete with, really."  He added, jokingly, "You have a pregnant, hormonal Colombian. She's ready to bust some heads. She ain't messing around.