"He made a throw, and he felt a little tightness," said manager Ron Washington. "We didn't want to push him any further, so we took him out. We'll evaluate him and see how he's doing tomorrow."
Washington added that he did not want to send Blalock back on the artificial turf at Rogers Centre, which has been known to cause and aggravate injuries.
Blalock was removed in the 10th inning, and Adam Melhuse replaced him at third base. Blalock had two hits in five at-bats during the game. So far this season, the 27-year-old slugger has hit .302 with two home runs and four RBIs.
David Singh is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.