Casas suffered the injury when he hit first base awkwardly trying to beat out an infield single in the second inning. He hit the bag and immediately crumbled to the ground, grabbing his left knee. Casas had to be carted off the field. Here's the play:

Boston Red Sox first baseman Triston Casas suffered a ruptured tendon in his left knee and is out for the remainder of the season.

Triston Casas suffered the injury when he beat a throw to first in Friday's game, getting stretchered off the field afterward.