Gregorius suffered the injury in the first inning of Sunday's 10-2 Yankees win, when he collided with Toronto Blue Jays first baseman Kendrys Morales while beating an infield single. He received attention from Yankees medical personnel but remained in the game and scored a run later that inning.
"It's something that we'll kind of monitor over the next 24 hours. It could potentially be a DL thing," Boone said. "So, not great there, but we'll just kind of see where we are tomorrow. Nothing broken or anything like that, but he's got a pretty significant bruise on his heel. There's some swelling in there."
Gregorius, who is batting .270 with 22 home runs and 74 RBIs, took the field at the top of the second inning, but Ronald Torreyes replaced him at shortstop before the top of the third.
The 28-year-old went to New York-Presbyterian Hospital for more tests.