Pujols was scratched from Monday's 13-8 victory over the Boston Red Sox with back tightness. The three-time NL MVP got an anti-inflammatory shot and is expected to be out of action for the next couple of days."He received an MRI today and then an injection to put him over the hump, make him feel better," general manager John Mozeliak said. "He's day to day. We'll see how he feels on Wednesday."The Cardinals are off Tuesday.Pujols missed a week this spring because of lower back pain he described as feeling like spasms. He returned to play in five exhibition games before being pulled from the lineup against Boston."We are going to get it treated and take a look at it," manager Tony La Russa said from Kissimmee, where the other half of the Cardinals picked up a 6-4 win against the Houston Astros. "I think right now if we take care of it, he should be fine."Mozeliak said Pujols has felt some discomfort in recent days. Asked whether he thought the star first baseman's back could be a chronic concern throughout the season, Mozeliak said: "I don't get that sense."Boston's lineup included two players with significant major league experience, shortstop Bill Hall and outfielder Jeremy Hermida, and the Red Sox still tagged former teammate Brad Penny for seven runs and 10 hits in five innings."You come out against a team you really don't know anything about and they're all swinging first pitch," Penny said. "It's kind of hard to work on setting a hitter up. In a regular-season game I'll be moving people's feet a lot more if they're going to be swinging first pitch."Penny has a 7.97 ERA in 14 2/3 innings."I've had some really bad springs before," the right-hander said. "Once the season comes your adrenaline gets going, it's easier to focus, it's more meaningful."Holliday hit an RBI double in his first game since March 9. He was nursing a strained muscle in his rib cage."I probably could have played one day earlier but they wanted a couple of days of batting practice, clear a couple of hurdles," he said.Holliday was slated to play left field before being switched to designated hitter because of the wet conditions. He should play the field Wednesday.Holliday and Pujols have played one game together this spring."As long as we're both in there on April 5," Holliday said. "We don't need to be in the same lineup, it's not like we're the quarterback and wide receiver."Hermida went 2 for 2 and scored two runs for Boston. Tug Hulett had two hits and three RBIs.