Shaw fouled a ball hard off of his foot in the fourth inning of Wednesday's 11-6 win over the Rangers, then came out of the game in the eighth inning. A fluoroscan taken at the ballpark during the game was inconclusive.
The left-handed-hitting Shaw is having a solid first full season in the Major Leagues, hitting .274 with nine homers, 48 RBIs and an .801 OPS.
Marco Hernandez is currently the backup third baseman for the Red Sox. Brock Holt, who recently returned from the disabled list and has played mainly left field this season, is also comfortable at the hot corner.
The Red Sox open a three-game series against the Marlins at Fenway Park on Friday leading up to the All-Star break.