Tommy Hunter will move up in the rotation and pitch on three days' rest vs. the Rays on Tuesday and the club is preparing to bring back Derek Holland from Triple-A Oklahoma City on Wednesday to replace Harden in the rotation.
The Rangers recalled outfielder Brandon Boggs from Triple-A Oklahoma City on Sunday to replace Harden on the roster.
"It's just tight," Cruz said. "There is not any other pain. I just don't want to take any other risks."
If Cruz is not ready in a couple of days, he could end up on the disabled list as well. He has already been on the disabled list twice this year with hamstring injuries.
"Once again, we're talking about a hamstring," manager Ron Washington said. "We want to make sure it doesn't get any worse. He's such a valuable asset, we've got to watch it."Harden has made just two starts since coming off the disabled list with a strained lower back muscle. He lasted just 2 1/3 innings in his last start against the Athletics on Aug. 7, giving up three runs and throwing 65 pitches.
He will report to Triple-A Oklahoma City on Tuesday to begin a rehab assignment with limited pitch counts.
Holland, who is 6-2 with a 1.91 ERA in 10 starts with Oklahoma City, lasted just 2 1/3 innings in his last start on Friday against Las Vegas. Holland threw 59 pitches while allowing three runs. He is 2-1 with a 4.19 ERA in four starts and one relief appearance at the Major League level this season.
T.R. Sullivan is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.