Boston Red Sox first baseman Triston Casas has been diagnosed with a fractured rib and is expected to miss significant time, dealing another blow to an injury-ravaged infield. Manager Alex Cora announced the news on Tuesday in Cleveland, where the Red Sox are facing the Guardians. Casas, who has been a key contributor to the team’s early season success, suffered the injury while swinging a bat during a home series against the Guardians last week. The 24-year-old has been hitting .244 with six home runs and 10 RBIs through his first 22 games. Bobby Dalbec, who has been filling in for Rafael Devers at third base, will move to first base in Casas’ absence. The Red Sox have been struggling with injuries throughout the infield, with Devers battling a knee injury and Trevor Story out for the season with a shoulder injury. Despite these setbacks, the Red Sox enter Tuesday’s game with a 13-10 record, 2.5 games behind the Baltimore Orioles and New York Yankees for first place in the American League East.