A pitch thrown by Yankees right-hander Bryan Mitchell pinched Souza's pinky, resulting in a deep laceration that required stitches. Souza finished running the bases and scored in the Rays' four-run eighth. He did not return to the field for the bottom of the inning.
X-rays of the finger were negative, but Souza said he will undergo further tests on Monday in Kansas City.
"It was a really deep cut, it was deeper than the doctor thought it was when he opened it up," Souza said. "We don't know what's in there. We're going to see a specialist in Kansas City.
"It's just my pinky. A giant laceration that runs up my pinky. I can't really bend it too well now. I'm hoping I wake up tomorrow and it feels little better. But I don't have much feeling in my pinky right now, which is kind of a worry for us. So we'll go from there."
Bill Chastain is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.