ARLINGTON -- The Rangers have placed first baseman Mitch Moreland on the disabled list and expect him to be sidelined for four to six weeks because of a strained left hamstring.
The Rangers used Moreland's spot to add Roy Oswalt to the roster. They also made room on the 40-man roster by designating Triple-A Round Rock pitcher Mark Hamburger for assignment.
Moreland injured his hamstring running to first base during Tuesday's game in San Diego.
"You don't ever want to be on the DL," Moreland said. "You don't ever want to be hurt. You want to be healthy and helping your team. That's not the case. I'm here now. I'm just going to do everything to come back healthy and do what I can off the field to support the team any way I can. As soon as I get back healthy, maybe I can help them on the field again.
"I've never done this before. I've never had an injury like this, so I wasn't really sure what the diagnosis would be. I talked to a few guys. They said it's a tough injury. It's something you really want to stay on top of and stick with your treatment."
With Moreland out, the Rangers went with Mike Napoli at first base on Friday against Rockies left-hander Christian Friedrich. Adrian Beltre served as the designated hitter, with Michael Young at third base and Yorvit Torrealba catching.
Against right-handers, Texas could start Leonys Martin in the outfield, Young at first base and use DH to rest one of their outfielders: Josh Hamilton, David Murphy or Nelson Cruz. That could prove particularly useful on this 10-game homestand with the weather expected to approach 100 degrees.
"It's a way to keep those guys fresh," manager Ron Washington said.
T.R. Sullivan is a reporter for MLB.com. Read his blog, Postcards from Elysian Fields, and follow him on Twitter @Sullivan_Ranger. This story was not subject to the approval of Major League Baseball or its clubs.