Pujols was removed from the Cardinals' game on Saturday against the Cubs due to a strained right oblique muscle, and it's unclear when he will be able to return. He will almost certainly be placed on the disabled list for the first time in his career, if not Sunday, then no later than Tuesday.
"There is serious concern," said Dr. George Paletta, "and it is the type of injury that we need to evaluate initially and again 18-24 hours later to get a better handle on it."
With one out in the top of the second inning, Pujols chased a short foul popup by Chicago third baseman Aramis Ramirez. He stopped short of catching the ball, and television replays showed that he grabbed at his right lower back on the play. The injury is in the rear of his torso, which is somewhat unusual in the case of oblique strains.
"He's going to miss a significant period of time," said manager Tony La Russa. "Anywhere from little significant to real significant. We can't tell for another 18-24 [hours]. But it's something we've got to deal with."
Cardinals assistant athletic trainer Greg Hauck and La Russa came out to check on Pujols when he first sustained the injury, but he remained in the game for the remainder of the second. His spot did not come up in the bottom of the third inning. When the Cardinals took the field defensively for the top of the third, John Rodriguez was inserted in left field and left fielder Hector Luna had moved to first base.
Pujols, the reigning National League Most Valuable Player, has missed just two games this year. He has never played fewer than 154 games in a Major League season. He has played through a slew of ailments, including an elbow injury in 2003 and plantar fasciitis for the past two years.
None of those injuries sent him to the DL. This one, however, is not one that he can simply play through and try to endure the pain.
"This is an injury that we are going to be extremely cautious with, because if you send the guy out there too early, then you have a major setback and a major re-injury," Paletta said.
"This is not an injury that he can go out and play with it sore, because that will put him at risk. He can't play at 60 or 70 percent."
Neither Paletta nor La Russa was willing to venture a guess as to the time Pujols will be out, but it's extremely unlikely to be short.
"If you told me right now he'd be out two weeks, I'd buy you dinner the rest of the year," La Russa said in his postgame news conference.
Oblique injuries are notoriously tricky -- as the Cardinals learned with Woody Williams in 2002 -- and this one does not appear to be a minor one.
"We grade them one, two and three," said Paletta. "One means it possibly stretched a little bit, two means it tore a little bit and three means it tore. So there is always tearing involved. If he comes in tomorrow and if he can rotate pretty well with little soreness, you can call this a mild or grade 1. If he can't rotate his trunk well, then this is severe and is grade 2 or grade 3."
The Cardinals were already playing with two players on the active roster but who were unavailable -- Scott Spiezio, who is ill, and Jim Edmonds, who has a strained abdominal wall. At least one of those players will have to be placed on the DL on Sunday, perhaps two.
Among the options at Triple-A Memphis are outfielder Skip Schumaker, infielder-outfielder John Gall and first baseman-outfielder Chris Duncan. First baseman Brian Daubach has hit well for Memphis, but is not on the 40-man roster.
The 2005 season saw the Cardinals make do at various times without many of their key players. Scott Rolen, Larry Walker, Reggie Sanders and Yadier Molina all spent lengthy stretches on the disabled list. But never have the Cardinals had to reconfigure their offense to accommodate Pujols' absence.
"We win as a team, we lose as a team," said shortstop David Eckstein. "No matter who it is, it gives someone else the opportunity to step up."
Matthew Leach is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.