Smith (elbow) won't pitch his simulated game until Wednesday, Tim Britton of The Providence Journal reports.
Smith is experiencing some residual lat stiffness, although the Red Sox still think he'll be able to begin a rehab assignment over the weekend despite the setback. If all goes as planned, it's reasonable to expect the reliever back before the end of the month, although a firmer timetable for his return should emerge once he gets a few rehab appearances under his belt.