Sanchez (foot, quad) had a setback in his rehab assignment Sunday with Triple-A El Paso, AJ Cassavell of MLB.com reports.
Eric O'Brien of CBS 4 adds that El Paso manager Rod Barajas said that Sanchez left his most recent game due to quad tightness. It's unclear how severe this new ailment is or how long it will be until Sanchez returns to action, but more should be revealed in the coming days.