"Spring Training was so long. I think I peaked a little early," Marshall said Thursday morning. "I was getting a little bit of fatigue in my shoulder. It's just precautionary. They have me doing some therapy and getting it strong again. I'm probably a day or two away. I'll probably be ready by Friday night's game."
Marshall was last used in a big league Spring Training game on March 22. Had the club placed him on the 15-day disabled list, he wouldn't have missed much regular-season time. But the DL is no longer a concern.
During Monday's 13-inning loss, Marshall got up briefly to warm up and threw at about 75 percent intensity. He has thrown in other bullpen sessions on the side and has taken it easy to prevent a setback.
"I've made good progress," Marshall said. "Guys have stepped up, big time. We've got a very capable bullpen. All of those guys can get any guys out in mostly any inning. They told me they would pick me up while I was down, and hopefully I can pick them up sometime during the season when maybe they're hanging a little bit."
Mark Sheldon is a reporter for MLB.com. Read his blog, Mark My Word, and follow him on Twitter @m_sheldon. This story was not subject to the approval of Major League Baseball or its clubs.