Rays manager Joe Maddon said he will "more than likely" not start Upton on Saturday as a precaution.
The injury occurred during Upton's only at-bat of the game in the first inning on a pitch that jammed him. His foot proceeded to get stuck in the batters box as he stumbled to first base.
"It's not bad at all," Upton said. "I'm not so sure I won't be able to play tomorrow. I think it was just precautionary.
"The trainers didn't know exactly what it was. They were afraid it was going to be a [hamstring], and it's not. That's a good thing."
Justin Ruggiano, who was called up from Triple-A Durham before Friday's game, filled in for Upton in centerfield.
Anthony Chiang is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.