Tenn. Code Ann. § 50-5-208

Application for an order pursuant to this part may be made by the minor, or the minor's parent, or legal guardian, or guardian ad litem appointed pursuant to this part. For the purposes of any proceeding under this part, a parent or legal guardian, as the case may be, entitled to the physical custody, care, and control of the minor at the time of the proceeding shall be considered the minor's guardian ad litem for the proceeding, unless the court determines that appointment of a different individual as guardian ad litem is required in the best interests of the minor.