The Yankees conclude the regular season on Sept. 29 against the Astros in Houston, but Rodriguez's hearing could be postponed if the Yanks qualify for postseason play.
It is anticipated that Horowitz's ruling on Rodriguez's suspension will not be reached until at least November.
Newsday reported that a preliminary hearing was held on Wednesday, when both sides met with Horowitz to go over the exchange of documents requested in the discovery phase and to set the hearing date.
Rodriguez, who was unavailable postgame, was suspended on Aug. 5 as part of MLB's investigation of Biogenesis, the now-shuttered Coral Gables, Fla.-based clinic that allegedly distributed performance-enhancing drugs to a number of professional athletes.
In a statement released that day, Commissioner Allan H. Selig said that MLB had levied the unprecedented 211-game suspension on Rodriguez because of "use and possession of numerous forms of prohibited performance-enhancing substances, including testosterone and human growth hormone, over the course of multiple years."
In addition, Selig said that Rodriguez's penalty was increased "for attempting to cover up his violations of the program by engaging in a course of conduct intended to obstruct and frustrate the Office of the Commissioner's investigation."
Rodriguez appealed the suspension, allowing him to return to the Yankees' lineup and play pending an arbitration decision. In 28 games this season, Rodriguez has batted .275 with four homers and 10 RBIs.
Bryan Hoch is a reporter for MLB.com. Follow him on Twitter @bryanhoch and read his MLBlog, Bombers Beat. This story was not subject to the approval of Major League Baseball or its clubs.