Diaz (biceps) threw a live batting practice session Wednesday, Bobby Nightengale of The Cincinnati Enquirer reports.
On tap next for Diaz should be a brief minor-league rehab assignment before he returns from the 15-day injured list. Hunter Strickland has seemingly built some security as the Reds' primary closer while Diaz has been sidelined with right biceps tendinitis, but Diaz should still have a high-leverage role in the bullpen waiting for him once he's activated.