"He's been bothered by it, and it's a concern," said general manager Brian Cashman. "We DL'd him to give it some time to calm down. I think he's running at about 75 percent now, and hopefully we can get him back to 100 percent."
Matsui aggravated the knee while playing two games in the outfield during the Yankees' series in Houston, and he would not have been able to perform any duties other than pinch-hitting this weekend, with National League rules in effect.
A .323 hitter with seven homers and 34 RBIs in 69 games this season, Matsui had not played since Sunday, allowing him to be retroactively disabled to Monday.
"You hope it's only 15 days," Girardi said.
After having the knee drained for a second time on Friday, the decision was made to disable Matsui, allowing the Yankees to activate right-hander Sidney Ponson for Friday's Game 2 start at Shea Stadium. Matsui had arthroscopic surgery after last season to repair a problematic right knee, and while that was not believed to be an immediate option, the Yankees would not rule out a similar procedure.
"Surgery is always the next step, but we're hoping to avoid that," Girardi said.
The Yankees' other roster move between games of the doubleheader was to option right-hander Ross Ohlendorf to Triple-A Scranton/Wilkes-Barre, recalling left-hander Kei Igawa to pitch one inning before he, too, was optioned back on Saturday, when the Yankees purchased the contract of right-handed rookie David Robertson.
Ohlendorf gave up six runs in his Subway Series appearance on Friday, raising his ERA through 40 innings to 6.53, and Girardi said that he would resume starting at Triple-A in an effort to provide more innings to fix his flaws.
"We want him to work on secondary pitches to get his sinker back, and we want him to work on his split," Girardi said. "We're going to start him, because he'll see multiple innings. The hard thing about being in the bullpen, a lot of times, it's hard to work on stuff, because you never know when you're going to be needed."
Cashman said that the Yankees had a meeting on Friday about Ohlendorf, and that the sinkerballer's move was not indicative of a change in the organization's thinking.
"It stretches him out a little bit, not because we think of him as a long reliever, but because we think it speeds up his developmental process," Cashman said.
Injured rookies Phil Hughes and Ian Kennedy are also making incremental progress. Kennedy (lat strain) was scheduled to make his second rehab start on Saturday for Class A Tampa, while Hughes (fractured rib) is expected to begin pitching in games in three weeks, putting his timetable for a Major League return in seven to eight weeks.
Additionally, right-hander Chris Britton (pulled rib-cage muscle) was scheduled to pitch in a Minor League game on Tuesday, having thrown two bullpen sessions already. Brian Bruney (right foot) was to throw one more bullpen session on Tuesday before resuming game action. He is expected to rejoin the Yankees' bullpen shortly after the All-Star break.