Harrison had a shutout going when he experienced some stiffness and was lifted after five innings.
"In the third inning it was stiff on me and it took a couple of batters to get back to normal," Harrison said. "Then after that I came in and asked for a stretch after the fourth. They asked what was wrong and I said, 'Nothing, it's just stiff.' I went back out for the fifth and after that they told me I wasn't going back out."
The left-hander went through his normal workout routine Monday, but he is going to stay away from any weightlifting that would put stress on the back.
Manager Ron Washington is confident Harrison won't miss any time.
"It was him saying he felt some stiffness and us reacting to it," Washington said of taking him out of the game. "It would have been very bad if we had left him out there and if he would have thrown a pitch and something happened."
* Craig Gentry said his ankle feels good and he is ready to play when needed. Gentry sprained his ankle in Friday's game against the Rockies when he landed awkwardly running to first base. He is not in the lineup tonight.
* The Rangers have won five series in a row and 12 of their last 15 games, but David Murphy still doesn't think they're playing their best baseball.
"I feel over the course of the last four or five days, we've played pretty well," Murphy said. "As a whole, we've had a lot of success the past two weeks to get to this point. But over those past two weeks, I don't feel we've really played great baseball.
"Take Josh Hamilton for instance. He's going to be Josh Hamilton before the end of the year, but he's going through a little slump right now. That usually doesn't happen. It's hard to say that we're clicking on all cylinders right now when our best hitter isn't himself."
* Rangers television play-by-play announcer Dave Barnett will not return to the booth in Monday's series opener against the Detroit Tigers. Barnett is still being evaluated after having an on-air issue on June 18.