A fracture in Posada's right foot cost him 16 days on the disabled list, and while he has returned to action, it is still not without occasional discomfort.
"It gets tender toward the end; I can't lie to you guys," Posada said. "I think it just gets tired. I'll keep an eye on it and keep treating it."
Yankees manager Joe Girardi said that he considers Posada available to pinch-hit on Thursday, and if need be, he could enter the game as a defensive replacement.
"I don't know how long we'll deal with that," Girardi said. "Eventually there will come a day when it doesn't fatigue and get sore. I can't tell you when that day is going to be."
The Yankees are hopeful that Posada will be able to catch two of three days in each of the team's upcoming Interleague series in Arizona and Los Angeles, where they will not have the luxury of the designated hitter rule.
Girardi said that he did not think it would be an issue, but Posada was not interested in looking that far ahead.
"I worry about today and tomorrow," Posada said. "I can't really get ahead of myself. It's one day at a time for me right now. ... It's just getting better. Yesterday is better than Sunday. As soon as it goes away, it would be great. There's still a little pain there in the last part of the game."
When Posada proves he can reliably catch without discomfort, the Yankees will drop the third catcher on their roster, journeyman Chad Moeller. Girardi said that it was something they would have to discuss, but he expected that New York would stay at 12 pitchers when Posada is cleared.
"My thoughts are that you have to feel that he's out of the woods and he can catch a game without experiencing what he's experiencing," Girardi said.