Damon crumpled to the ground on Friday after making contact with a Brad Penny offering, driving it into himself. He exited the game after the half-inning and had to watch the rest of the Yankees' 20-11 rout of the Red Sox.
"I wasn't really too worried," Damon said. "I just knew that it could be a short night for me. I was in a lot of pain, and after we pulled up my pants, we saw the bruising. We were more worried about how much swelling I was going to get."
Attended to on the field by Yankees manager Joe Girardi and head trainer Gene Monahan, Damon completed his at-bat, striking out looking against Penny.
When the Yankees took the field for the bottom of the first inning behind Andy Pettitte, Damon exited to be examined and was replaced by Eric Hinske in left field.
Girardi said that he was uncertain if Damon would be available for Saturday's late-afternoon start at Fenway Park.
"I don't know if he'll be able to play," Girardi said. "We'll just have to wait and see. He'll be day-to-day. Hopefully it doesn't linger. I know it was pretty sore when he came out.
"It scared me. I thought, 'Oh boy, we don't need this.' Physically, he's been really good for us this year. He's had a great season. You don't want to see something like that."
Damon is hitting .284 with 22 home runs -- two shy of his career high, set in 2006 -- and 68 RBIs in 112 games for New York.
Hinske completed the game going 2-for-4 with two doubles and a RBI, though he did misplay a ball in left field against the Green Monster.
Hinske lucked out, as the ball struck the wall and ricocheted back to the infield, where Derek Jeter and Alex Rodriguez teamed to complete an unorthodox 6-5 putout on Dustin Pedroia in the third inning.
"I'm especially happy for Eric Hinske, to do what he does," Damon said. "He got some big hits for us and hopefully, whatever the lineup is tomorrow, he can do the same if I'm not in there."
Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.