Sanchez reported "slight discomfort" in his throwing shoulder Wednesday, Jordan McPherson of the Miami Herald reports.
Sanchez started a simulated game at the Marlins' alternate training site Wednesday but was removed early due to his injury. The Marlins were prioritizing his long-term health by keeping him off the Opening Day roster, but it's safe to assume that the team will be extra cautious with the 22-year-old now that he's dealing with a shoulder issue. The team will reevaluate Sanchez before determining the next steps in his recovery.