The Rangers called up reliever Alexi Ogando from the Minor Leagues. He will work out of the bullpen. The Rangers, because of the off-day Monday, won't need a starter to replace Harden until Saturday when they face the Houston Astros at Minute Maid Park.
Left-hander Matt Harrison, who started the season in the rotation but is now a long and middle reliever, is the leading candidate to take that spot. Much will depend on how much Harrison is needed between now and Saturday. He is in the bullpen for this weekend's series in Milwaukee.
"The last thing I want to do is jerk him back and forth," Rangers manager Ron Washington said. "But if we're going to go there, he gives us the best chance of giving us five innings."
Dustin Nippert is another possibility, and the Rangers could look for somebody at Triple-A Oklahoma City. Guillermo Moscoso (3-2, 3.80 ERA), Doug Mathis (1-2, 5.00 ERA) and left-hander Michael Kirkman (6-1, 3.17 ERA) are all possibilities. Derek Holland and Brandon McCarthy are on the disabled list and not options at this point. But Washington made it clear that it will likely be Harrison.
"Whatever they want me to do," said Harrison, who is 1-1 with a 4.97 ERA in six starts and three relief appearances.
He was 1-1 with a 5.29 ERA in six starts before going on the disabled list with inflammation in his left biceps. He was moved to the bullpen when he came off the disabled list and has a 3.52 ERA in three relief appearances since being activated on May 29.
Harden goes on the disabled list with a record of 3-3 and a 5.68 ERA. He is also 1-2 with a 7.60 ERA in his last seven starts since throwing seven scoreless innings in a 4-2 victory over Oakland on May 3. He leads the American League in walks, is second in home runs allowed and has the fifth-highest ERA in the American League. His 15.78 baserunners per nine innings is tied for the highest in the league.
He pitched six innings and threw 120 pitches in a 6-2 loss to the Brewers on Friday night. The Rangers said the muscle has been bothering him for some time.
"He hasn't been pitching at 100 percent," general manager Jon Daniels said. "He has been on the injury report. Nobody is more frustrated than Rich. So we put our heads together and said, 'Let's knock this out completely.'"
Harden is expected to undergo an MRI this week to make sure there's not a more significant injury. Harden said he really felt the injury running to first base in Friday's game. He dropped a sacrifice bunt and grounded out in his two plate appearances against the Brewers.
"It's been there for a while," Harden said. "What can I say? ... Yesterday I ran to first a couple of times, and it got worse. It's something I've been dealing with. It's been nagging me for some time."
The Rangers signed Harden in the offseason to a one-year, $7.5 million contract with a mutual option for 2011. They did so even though he has a history of injuries. This will be the eighth time Harden has been on the disabled list in the last five years.
"It's not something I wanted to do," Harden said. "I've been working hard to keep myself off there. But at this point, it's the best decision to get myself right and pitch like I can."