Christina Aguilera, Cee Lo Green, Blake Shelton and Adam Levine will return for a second season of "The Voice," which is ailing network NBC's most successful new show in years.

NBC said on Thursday that all four "coaches," who help the contestants hone their skills in the music talent contest, would take part in a second season, but the network did not say exactly when the new set of shows would begin.

Some industry watchers speculate that NBC may try to challenge Fox's juggernaut "American Idol" when it returns to airwaves in the winter of 2012.