JUPITER, Fla. -- Eight days away from opening the season in Arizona, the Cardinals have growing concerns about whether two key position players will heal in time to be ready for that April 1 game.

Carlos Beltran (right toe injury) has not played since returning from the World Baseball Classic, and minutes before Sunday's game, David Freese had to come out of the lineup due to back tightness. With only five spring games remaining, manager Mike Matheny expressed concern about the tightening window those two players have to get back on the field.

Beltran did get some work on Sunday out on the backfields of the Cardinals' complex, where he played five innings in a Minor League game. He went 1-for-5 and made one play in the field, Matheny said. It's the outfield work that the Cardinals see as most pressing for Beltran, who took 32 at-bats while playing in the Classic.

"We've got to really do some close monitoring," Matheny said. "His is going to be more the movement stuff. We need him to be able to take care of what he has to take care of in the outfield."

Freese has played inconsistently since bruising his tailbone when he tumbled into the stands trying to make a catch in foul territory on March 4. He returned to the field on Thursday after a six-day layoff, but has sat out all weekend. Freese informed the medical staff that his back tightened up on him during pregame work on Sunday.

"I don't know the severity except we don't have that many days until we have to be ready," Matheny said after the team's 10-7 loss to the Mets. "As a matter of fact, it looks like we have a week. He hasn't had a lot of at-bats and we have to have him being ready for whatever."

Freese has taken 30 at-bats in Grapefruit League play, 16 of those coming since the initial injury. Pressed further about his concern over Freese's latest setback, Matheny said: "The questions you all have are legitimate. And the questions I have running through my mind ... you're always trying to figure out what you're worst-case scenarios are and try to have some contingency plans."

The contingency plan would begin with Matt Carpenter, who is expected to start at third base on Monday. Neither Freese, nor Beltran, will take the trip to Fort Myers, Fla., to face the Twins.

Even if Freese is cleared to take the field before camp breaks, the Cardinals will consider keeping him out of Grapefruit League games. In doing so, the club would maintain the flexibility of being able to backdate a stint on the disabled list, should Freese need to start the season on it.

Teams can backdate a DL placement to March 22, if a player doesn't appear in a Grapefruit League game from that point forward. That would reduce the stint from a mandatory 15 days to only five. Because Freese played in Friday's game, the Cardinals would be permitted only to backdate nine days.

Beltran may follow a similar track, also leaving the Cardinals room to backdate a DL assignment, if needed. Beltran said on Friday that his right toe, which was hit by a pitch on Feb. 28, continues to bother him on defense and when he swings from the right side.

Matheny said he would have "no hesitation" putting either Freese or Beltran on the Opening Day roster if their only playing time over the next week comes in Minor League games. At this point, the Cardinals just want to see both players get the work somewhere.

The Cardinals endured another brief injury scare on Sunday when left fielder Matt Holliday fouled a pitch off his left ankle. Scheduled to play a full nine innings, Holliday exited the game after the at-bat. He appeared, however, to have no issue walking off the field.