Middleton (forearm) will throw a bullpen session Saturday, Jeff Jones of the Belleville News-Democrat reports.
Middleton has been on the 15-day IL since the start of the season after sustaining a right forearm strain in mid-March. He recently extended his throwing distance to 110 feet with no setback, and the right-hander has progressed enough to take the next step in his rehab program. Middleton will likely need multiple bullpen sessions without issue before beginning a rehab assignment.