Rangers starting pitcher Matt Harrison left Sunday night's start after five scoreless innings against Colorado because of soreness in his left hip.
Harrison was examined by team physician Dr. Keith Meister, who determined that the problem was caused by lower back tightness on the pitcher's left side. Harrison will be evaluated further over the next couple of days.
Harrison left with a 4-0 lead and was in line for his 10th victory over the season.
When Harrison came into the dugout after the fifth inning, he could be seen talking with manager Ron Washington and pitching coach Mike Maddux. The left-hander was clearly pleading his case that he felt fine and wanted to keep pitching.
Rookie lefty Robbie Ross took over on the mound to start the sixth.