Boston Red Sox outfielder Mookie Betts left after the fourth inning of Saturday's game against the Tampa Bay Rays with right hamstring tightness and is day-to-day, the team announced.
Blake Swihart entered the game to take Betts' place in left field, with Andrew Benintendi and Jackie Bradley Jr. shifting to center and right field, respectively.
Betts is off to a sizzling start for the Red Sox this season with a .344 batting average, eight home runs and 18 RBIs. Boston is 19-6 and leads the AL East.