Several Cardinals got their first taste of the Cubs rivalry at Busch Stadium on Friday night, Nolan Arenado and Dylan Carlson among them. One of the duo didn’t get a look in the encore on Saturday night -- and might not in Sunday’s series finale.

Carlson was a late scratch from the starting lineup Saturday with a tight back, the Cardinals announced about an hour and a half prior to first pitch, and he is considered day to day.

Manager Mike Shildt said after the Cardinals’ 2-1 win that Carlson felt his back tighten up pregame and it didn’t loosen up enough to allow him to play. Carlson was getting treatment Saturday night, and the club will re-evaluate him Sunday.

“Nothing that we think is going to be too lingering,” Shildt said, “or maybe hoping that to be the case.”

Lane Thomas slotted into right field Saturday, lacing a game-tying knock in the fifth inning, while Paul Goldschmidt moved into the No. 2 spot as the rest of the lineup shifted up.

Saturday marked only the third time Carlson was out of the starting lineup this season.

Any interruption to Carlson’s season would pause a promising rookie campaign for the 22-year-old. With a .291/.382/.424 slash line, he leads the Cardinals in on-base percentage and ranks among the top rookies in several offensive categories. He’s done it while making most of his starts at center field, though he’s been able to get back to his more natural right field with the return of Harrison Bader.

And any time without Carlson will complicate the Cardinals’ outfield picture, already without Tyler O’Neill (left middle finger fracture on Sunday), who remains on the injured list but is starting to ramp back up.

Thomas and Justin Williams -- who’s started in place of O’Neill -- will likely serve as the Cardinals’ primary corner outfielders until either returns. Or Matt Carpenter could make starts at second base, which would allow Tommy Edman to play in right.

Bird droppings
• Andrew Miller (right foot toe blister) is set for a rehab assignment early next week with Triple-A Memphis, manager Mike Shildt said. Miller threw a “heavy” bullpen session on Friday, and how he reacts to playing catch on Saturday will determine his exact timeline.

The return of a healthy Miller will be a positive development for the Cards. With Tyler Webb struggling, Génesis Cabrera sits as the most dependable lefty in a bullpen with only two healthy southpaws.

• Paul DeJong (non-displaced left rib fracture on May 12) has yet to resume baseball activities.

• Right-hander Seth Elledge was optioned to Memphis to allow for the return of Miles Mikolas on Saturday night. Elledge was among several relievers who struggled on Friday, tagged for three runs, four hits and one walk in two-thirds of an inning.