Drew Pomeranz was unable to complete a side throwing session Thursday because of pain in his left biceps leaving him headed for the disabled list and Collin McHugh as his likely replacement in the Rockies' rotation according to major-league sources.

Pomeranz has been unable to get on track since his call-up last month losing all four of his decisions and posting an 8.10 ERA. He lost Monday to the Marlins a team that hadn't scored in 37 consecutive innings before facing him. Rockies manager Walt Weiss would not commit to Pomeranz making a start Saturday until his side session Thursday. It didn't go well.