"It's the first time this year that I've felt really bad," Damon said. "We know that I definitely need my legs to help this team."
Damon said he is in the early stages of figuring out just how bad the injury is. While he could not completely rule out that the arch might force him to the disabled list for the first time in his career -- a recurring threat over the last two seasons -- Damon did say it would take "a miracle" for him to play on Wednesday.
With Hideki Matsui's swollen left knee likely keeping him out of defensive duty in Pittsburgh, the Yankees moved to reinforce their outfield on Tuesday by purchasing the contract of Justin Christian from Triple-A Scranton/Wilkes-Barre and placing him in the starting lineup for his Major League debut.
Girardi said that he planned to give Damon at least one day off in this series after the update was delivered on Sunday. Damon has not yet been sent for tests, though he could be if the injury persists.
"We just figured we'd see how he was Tuesday," Girardi said. "He's played a lot. A couple of days of treatment [may] help it."
Damon said he struggled moving on the field Sunday, whether he was running to the outfield or turning on his back leg while batting. He first felt a tweak during batting practice, and it got worse as the day progressed.
"I'm trying to think if I slipped anywhere," Damon said. "It just hit me as the day went on. As I had to get ready for the game, it just kept getting worse."
The hottest hitter in the Majors since May 20, batting .413 over that span, Damon took an 0-for-4 against Cincinnati on Sunday and said he should have hit the pitches he missed.
"I had no chance to swing the bat or run after a ball," Damon said.
The Yankees had firsthand experience with a serious foot injury last May, when Jason Giambi tore the plantar fascia of his left foot while running out a home run at Rogers Centre in Toronto.
Giambi did not return to the Yankees until August, and while Damon said his injury isn't nearly as bad as the plantar fasciitis that slowed Giambi, he also doesn't want it to escalate.
"I don't want it to get to the situation where it's what happened to Jason," Damon said.
The Yankees are also playing somewhat short-handed in National League ballparks because Matsui's left knee is not ready for defensive duty, having been aggravated during the series at Houston last week. Matsui had fluid drained from the knee last week and will likely be limited to pinch-hitting duty for the Pittsburgh series, Girardi said.