Diekman (abdomen) threw 31 pitches during a simulated game Saturday, Jeff Wilson of the Fort Worth Star-Telegram reports.
Diekman admitted to feeling fatigued afterward, but nevertheless he cleared the hurdle -- perhaps his final hurdle before heading out for a rehab assignment. He could join Double-A Frisco as soon as Tuesday if his arm responds well. The lefty underwent three operations earlier this year to address ulcerative colitis.