Matsui -- hitting .323 with seven home runs and 34 RBIs in 69 games -- aggravated his knee by playing the outfield in two games during the Yankees' Interleague series at Houston.
The Yankees play one of their games on Friday under American League rules, creating the possibility that Matsui could at least DH in the first game of their two-stadium doubleheader against the Mets.
Matsui said he could play if needed, but he does not know if the team will decide to use him. Resting for the entire weekend could help.
"I think it would benefit me, but I also think it would benefit the team," Matsui said through an interpreter.
Girardi said that the Yankees will take a look at Matsui before Friday's afternoon game at Yankee Stadium. Matsui had fluid drained from his knee last week, and Girardi was not impressed by his batting practice swings in Pittsburgh, where he appeared to shy away from putting weight on his back leg.
"If your legs aren't under you, it's hard to be productive," Girardi said. "Sometimes you get in bad habits as a hitter because you're favoring something."
In the event Matsui finds himself in the lineup for DH duty against Mets right-hander Mike Pelfrey, he said that his timing would not be a problem, as long as he took some batting practice before that game.
"Even if I hit every day, my timing can be off," Matsui said.
The Yankees did regain one outfielder on Thursday, placing Johnny Damon back in left field after he had missed the first two games of the series at PNC Park.
Damon had been slowed by a sore left arch on Sunday in New York's final game against Cincinnati and even spoke about the possibility of requiring a DL assignment, but Girardi said he believed Damon would be fine.
"I'm very confident," Girardi said. "He came in my office today and said, 'I'm ready to go.' We'll watch him carefully and just make sure he feels OK. We won't abuse him."