Papelbon (ribs) threw a 40-pitch bullpen session Saturday, William Ladson of MLB.com reports.

EDGE Analysis

The intercostal muscles which Papelbon strained in mid-June did not present any issues during the side session. He may need to face live hitters once or twice, but Papelbon appears to be inching close to a rehab assignment. While Shawn Kelley has filled in admirably in Papelbon's absence, it would be a surprise if Papelbon didn't return to the closer role upon activation.