St. Louis Cardinals catcher Ivan Herrera was injured running the basepaths Sunday and had to exit the team’s 5-4, 10-inning loss against the Red Sox in Boston in Game 1 of a doubleheader.

Herrera was unable to put weight on his left leg while leaving the game. The Cardinals called the injury “left knee inflammation” in an update afterwards.

The four-year pro required assistance walking off the field in the third inning after reaching base on a walk, then making it to third on a Nolan Arenado single to left. A popout ended the inning and scoring threat, at which point manager Oliver Marmol and trainer Adam Olsen helped Herrera reach the dugout.

Herrera, 24, was off to a hot start this year, batting .400 with four home runs in 20 at-bats over six games headed into the day. He went 0-for-1 with a walk in Game 1 to lower his average to .381.