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The Boston Red Sox have lost yet another player to injury. First baseman Triston Casas was placed on the 10-day injured list over the weekend with what was originally diagnosed as a left rib strain. That proved to an understatement as on Tuesday, Red Sox manager Alex Cora revealed that Casas has a fractured rib that will sideline him for "a while." (Catcher Tyler Heineman was called up in a corresponding move.)

Casas suffered the injury taking a swing in his first at-bat Saturday. He stayed in to finish the at-bat -- Casas did not take another swing and drew a walk -- and then was replaced defensively in the next half inning.

"He's not doing OK," manager Alex Cora said after the game (via the Boston Herald). "... We're checking on him, we'll know more over the course of the night. When he came in (after the at-bat), he said 'I can play defense, but you need somebody to hit for me.'"

Casas, 24, owns a .244/.344/.513 batting line with six home runs in the early going this season. He has been an important middle of the order presence as injuries have taken players in and out of the lineup. Bobby Dalbec, who has been unable to cement himself as an everyday player the last few years, is likely to step in at first base while Casas is sidelined.

On the position player side, the Red Sox are already without second baseman Vaughn Grissom (hamstring strain), utility man Romy Gonzalez (wrist sprain), outfielder Tyler O'Neill (concussion), and shortstop Trevor Story (shoulder surgery). Third baseman Rafael Devers has been in and out of the lineup with shoulder and knee trouble as well.

The Red Sox are also without three rotation members: Lucas Giolito (elbow surgery), Nick Pivetta (elbow strain), and Garrett Whitlock (oblique strain). They have a league-leading 12 players on the injured list and are sixth in the league with 185 man-games lost to injury. Now they've lost one of their top hitters.

Boston is so short on players now that they're carrying three catchers -- Heineman, Reese McGuire, Connor Wong -- because they don't have any other healthy position players on the 40-man roster in the minors. They would have to cut someone to add a new player to the 40-man.