Overton (back) tweaked his hamstring while ramping up in Arizona and is without a clear timeline to begin a rehab assignment, Bobby Nightengale of The Cincinnati Enquirer reports.
Overton has resided on the 60-day injured list since May 23 due to a stress reaction in his lower back, but he was believed to be tracking toward a return at some point in September. Though he hasn't been shut down from throwing and will continue to do long toss, the hamstring issue presents a new hurdle he'll have to overcome before facing hitters and eventually pitching in games. He may not have enough time to build up for a starting role and may be relegated to the bullpen if he rejoins the Reds at any point in 2022.