Fiers (elbow) will make a rehab appearance at Triple-A Las Vegas on Saturday, Matt Kawahara of the San Francisco Chronicle reports.
Fiers made his debut in Las Vegas as a starter Tuesday and gave up three earned runs in 1.2 innings. He'll pitch out of the bullpen in Saturday's appearance since manager Bob Melvin said that the team wants to keep the option open of bringing the right-hander back as a reliever. A better idea of Fiers' status will likely be known based on his pitch count in Saturday's appearance, but he's likely close to returning if the Athletics don't need him fully stretched out as a starter.