Bay exited Wednesday's 6-4 loss to the Rays in the eighth inning, when he aggravated his right hamstring running out a grounder to short.
"I re-aggravated the tweak running down to first in the eighth inning there," said Bay. "It doesn't feel real bad but it's definitely going to be a couple of days."
After missing Sunday's game in Baltimore and Tuesday's opener at Tropicana Field, Bay returned Wednesday, thinking that the two games off would be just what he needed.
The strategy looked even better when Bay slugged a home run in the second inning of Wednesday night's game, his first since July 7.
By the end of the night, however, Bay wondered if maybe he came back just a little too soon.
"It's something I thought I could play with," said Bay. "I just went down the line, and it kind of grabbed me again. And now knowing, I guess, how I felt when I started today, maybe that's not good enough to play. I felt like it was and it kind of set me back a little bit. Knowing that now, I might take a few more days on top of that to make sure, but I don't think it's a long-term problem at all, no."
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.