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(TODAY) -- Just one week into season three of "The Voice," NBC is announcing big changes for cycle four. Coaches Christina Aguilera and Cee Lo Green, who have been with the singing competition since it launched, will be taking next season off. In their chairs will sit Usher and Shakira.

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Adam Levine and Blake Shelton are staying through season four.

"We are thrilled to welcome Usher and Shakira to 'The Voice,' " Robert Greenblatt, the chairman of NBC Entertainment, said in statement. "The addition of these popular iconic artists continues the tradition established by Christina, Cee Lo, Adam and Blake. Doing two back-to-back cycles of this show requires a tremendous amount of time, and we are happy to accommodate the commitments made by Christina and Cee Lo."

Aguilera has a new album, "Lotus," to promote and will be going on tour to support it. Green, meanwhile, is taking time off to work on new music and a scripted comedy about his life.

"'The Voice' has always been known for pairing incredible up-and-coming talent with superstar coaches who are top-level current artists," executive producer Mark Burnett added. "Having award-winning artists as coaches means they need to be able to tour. ... This is exactly why, after three seasons, we needed to allow them to rotate out so they can get on the road amongst their fans."

Both Aguilera and Green made it clear that they will be back after their hiatus.

"By pursuing my first passion of music during the break, I am also able to come back and offer even more to my team on 'The Voice' in the future," Aguilera said in a statement.

"Thank you, NBC, for supporting my decision to take this season four hiatus!" said Green. "I will return for season five and will be watching season four."

Though Shelton is expected to stay through next season, he may be the next coach to take a break from the hit show. In an interview with Access Hollywood, the country star said he didn't know how much longer he could do "The Voice."

"It's their decision (for us to leave), in that they're the ones choosing to do back-to-back seasons," he explained to Access. "They really leave us no other option ... if we want to tour, there's not a chance of that doing back-to-back seasons. That's not acceptable to me."

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