Tenn. Code Ann. § 23-2-103

Any attorney or solicitor who is employed to prosecute a suit that has already been brought in any court of record shall have a lien upon the plaintiff's right of action from the date of the attorney's or solicitor's employment in the case; provided, that the record of the case shall first be made to show such employment by notice upon the rule docket of such court, by a written memorandum filed with the papers in the case or by notice served upon the defendant in the case.