Diekman threw 27 pitches during a live batting practice session Monday, the Associated Press reports.
Rangers manager Jeff Banister called it a "very encouraging day" for the left-hander, who hasn't pitched competitively this season following three surgeries to repair his colon. With Diekman having completed multiple live batting practice sessions and simulated games since resuming his throwing program in July, it may not be long before he's cleared to begin a rehab assignment as he prepares for an eventual return to the Texas bullpen.