Rodriguez served as the designated hitter for the first time this season, pushing usual DH Hideki Matsui to right field and Bobby Abreu to the bench, with left-hander Brian Burres starting for the Orioles. In place of Rodriguez at third base was Morgan Ensberg, making his first appearance of the season at the hot corner.
Jorge Posada, who has caught in one game since April 8, was back in the lineup and back on the field -- but at first base, a position he had played 18 times in his 14-year Major League career, but only twice since 2002.
"We want to give Alex a day, as much as being a DH is a day," Girardi said, adding that the impending birth of Rodriguez's second child factored into the decision. "I kept thinking that his day would come in this 20-day stretch when Cynthia had the baby. Well, that day has not arrived yet. ... I felt we needed to give Alex a day, and this was the best way to do it."
Posada, who has been sidelined with a strained right shoulder, said he was able to catch on Saturday but accepted his manager's decision to use him at a different position.
"I'm a catcher," Posada said. "I'm playing first base today, but I don't know what's going to happen later. I see myself as a catcher later, just getting ready [for that position]. I like thinking the way I do as a catcher. ... If I have to help out the team by playing other positions, I will."
Posada wasn't needed behind the plate on Saturday, Girardi said, because Molina's gimpy hamstring was feeling much better after he pushed it in Friday workouts. Molina sustained the injury last Sunday and had missed five games.
"[Molina] said he was ready to go yesterday, and I said, 'You did a lot of work yesterday -- let's give it to today to see how it responds.' It responded fine, and he's out there," Girardi said.
Just in case, the Yankees are keeping catcher Chad Moeller around as an insurance policy. Posada hopes to be healthy enough soon to make Moeller expendable and create an opening for another bat off the bench.
"I don't know -- I'm thinking [Sunday] or Tuesday," Posada said when asked when he could handle the rigors of catching and throwing out runners.
The inactivity is starting to wear on Posada, who has always prided himself on being available.
"I hate not being a part of the lineup," Posada said. "I'm in there today, and I'm happy about that, but I want to be consistent and be behind the plate."
Pete Kerzel is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.