With two outs in the seventh inning, Pujols hit a ground ball to the left side. He felt discomfort in his leg about halfway down the baseline and pulled up, and so was thrown out, despite a late and offline throw from Miguel Cairo.
"I just felt a little tight, and I just pulled off," Pujols said. "I think I prefer it tight than a blown-out hamstring, you know? It's something that, I have to deal with it. It's been rough here the last week or so with the rain and all that, and our bodies take a little beating."
After Pujols descended into the dugout and the Cardinals' training staff looked him over, he was removed from the game. Lance Berkman moved to first base, with Jon Jay entering the game to play right field for Berkman.
Pujols has dealt with hamstring problems in the past, but declined to compare this instance to previous ones. He said he was still feeling some discomfort in the clubhouse after the game, but didn't sound overly concerned about the issue.
"I think this just all depends how I wake up tomorrow," Pujols said. "The test was pretty good. I don't think it's too bad. But it's something that, when I wake up tomorrow, I can sense it a little bit more about how I feel. So hopefully, it's not as bad as I feel right now, and I'll be glad that we have a day off tomorrow."
Matthew Leach is a reporter for MLB.com. Read his blog, Obviously, You're Not a Golfer and follow him on Twitter at @MatthewHLeach. This story was not subject to the approval of Major League Baseball or its clubs.