"It's not what we wanted to see," Girardi said. "I don't think he's healthy enough to go with us. We'll wait for the MRI tomorrow and see how he feels."
With Karstens sidelined, left-hander Kei Igawa and right-hander Darrell Rasner are the top candidates left standing to make the Opening Day roster.
Igawa (5.56 ERA) started against Pittsburgh on Thursday and wasn't his sharpest, allowing four runs and five hits in 3 1/3 innings, walking three and striking out two. Rasner (5.02 ERA) has pitched his best spring ball of late, but served up a three-run homer to Cleveland's Andy Marte on Tuesday.
"We have some things we need to sit down and talk about," Girardi said.
Long relief aside, the framework of the Yankees' roster is essentially set, despite the fact that 35 players still remained in camp as the club closed up shop at the newly-christened Steinbrenner Field.
New York made several cuts on Thursday, reassigning infielders Bernie Castro and Cody Ransom, outfielders Greg Porter and Jason Lane, and catchers Jason Brown and Chad Moeller to Minor League camp.
Several other items remain, particularly the role of a right-handed reliever, where Brian Bruney (2.00 ERA) and Ross Ohlendorf (1.86 ERA) appear to be the strongest candidates, though Jose Veras (9.00 ERA) is also in the mix. Left-hander Billy Traber (1.08 ERA) seems to be a lock to be on the 25-man roster, especially with Sean Henn beginning the year on the disabled list.
New York's four-man bench is likely to be comprised of Jose Molina, Wilson Betemit, Shelley Duncan and Morgan Ensberg, but non-roster invitee Nick Green remains on the roster, sticking with the Yankees after he recently turned down a contractual opt-out clause. Girardi said the club needed to have some further discussions to finalize Green's status.
"We're real close," Girardi said. "There are some people that we have to talk to."
One wrinkle is that the Yankees may decide to place Andy Pettitte on the disabled list retroactively with back spasms, allowing them to free a roster spot for Opening Day on Monday. Pettitte will pitch in a Minor League game on Sunday in Tampa and, if disabled, would be available to be activated on April 5 against the Rays.
Girardi said there is a chance that machinations could be still discussed after the Yankees' two-game trip to Dolphin Stadium, all the way on the charter flight back to New York, but he indicated it was more likely he and general manager Brian Cashman would finalize the roster by the close of business Saturday. In the event of another Karstens-like injury, the Yankees would at least have depth handy on the plane.
Many of the players slated to begin the year at Triple-A Scranton/Wilkes-Barre will fly with the club to New York and then drive the rest of the way to Pennsylvania, where they open the International League season on April 3 against the Lehigh Valley IronPigs.
"The thing that you worry about the next three days is what you worry about the whole Spring Training -- health," Girardi said. "We're real close."
Girardi added that depth had been the one characteristic of camp that stuck with him, reinforcing just how many tough decisions there were to make. One example was the case of 24-year-old outfielder Brett Gardner, who impressed with his ability to create havoc on the basepaths but was reassigned to Minor League camp on Wednesday evening, hours after a foul ball split his lower lip.
Calling a player into the office, Girardi said, is something that never gets any easier with practice.
"I absolutely hate it," Girardi said. "I know what it's like to want to get to the big leagues, and I know what it's like to get sent down. This year was no easier than 2006. I don't think it'll ever be easy."
For the next few days, though, the manager has no choice but to make those tough calls.