Diekman will begin a rehab assignment Thursday with Double-A Frisco.
When he takes the mound Thursday, it will mark Diekman's first appearance in a professional game since Oct. 9, 2016. The 30-year-old has faced a long road to recovery while undergoing three surgeries to repair and rebuild his colon, but he finally seems to be progressing toward a return after facing hitters in live batting-practice sessions and simulated games on multiple occasions in August. He's expected to throw 15 pitches in his first appearance for Frisco and may only need one or two minor-league outings beyond that before the Rangers activate him from the 60-day disabled list.