WASHINGTON -- First baseman Matt Adams left the Cardinals' 2-1 loss to the Nationals in Thursday's series opener at Nationals Park with mid-back stiffness. He considered himself day to day, but the Cards said he will be re-evaluated Friday.
Adams injured his back on a swing during his fourth-inning at-bat. Though he singled several pitches later and ran the bases without incident, Cardinals trainers determined he was best off exiting the game.
Cardinals manager Mike Matheny described the injury as a "little spasm." 
"It wasn't allowing me to swing the way I wanted to," Adams said.
With Adams out, Randal Grichuk entered the game in center field, Jeremy Hazelbaker shifted from center to left and Brandon Moss moved from left field to first.
Adams had been hot at the plate, batting .381 with four home runs in the month of May to raise his average to .320 on the season.