"It felt like it kind of got jammed a little bit when I went back in," Ackley said. "I couldn't really tell exactly what happened. I've never had any shoulder things in the past before, so it's hard for me to pinpoint what it was."
Ackley was replaced by Mark Teixeira in the seventh inning and said that while he felt able to swing a bat, throwing was difficult. Teixeira went 0-for-1 in his return to the lineup after missing four games with neck spasms, and he expects to play on Monday against the Blue Jays in Toronto.
"It was kind of a good first step, just to make sure I could do the normal things," Teixeira said. "I'm glad I didn't have to dive for anything today or get out of the way of a 95-mph fastball at my head. Hopefully it's over with."
Because of Teixeira's injury, the Yankees have been dipping into their depth options at first base this past week. In addition to Ackley, Girardi has started Austin Romine at first base, while mentioning that he also could use Brian McCann or Ronald Torreyes at the position.
"If Ack is down, we have to be a little bit more creative," Girardi said. "I'm not afraid to run Ro out there. We've been reluctant to move [Chase] Headley over there -- we did it a couple of times -- just because he's been playing third well and you hate to start moving everyone around."
Another potential option is to summon Nick Swisher, who continues to gather at-bats at Triple-A Scranton/Wilkes-Barre, where he has played first base, the outfield and DH. The Yankees also might consider big league veteran Chris Parmelee, who has posted a .768 OPS in 138 at-bats, compared to Swisher's .629 OPS in 131 at-bats.
"We'll just see what we have after the MRI," Girardi said.
Bryan Hoch has covered the Yankees for MLB.com since 2007. Follow him on Twitter @bryanhoch, on Facebook and read his MLBlog, Bombers Beat. This story was not subject to the approval of Major League Baseball or its clubs.