"Basically, yesterday I had a little cramp," Youkilis said. "That just turned into, 'We're going to be precautionary.' I'm fine. I could play today, and I'm perfectly fine, but they were just like, 'No, we're going to sit you out.'"
Youkilis said that if this were the regular season, there would be no question about him playing.
"I don't think it's anything serious," Girardi said. "We're being really cautious right now, because we can be."
Youkilis said that this does not feel like the oblique injuries he has had in the past; he can swing the bat, but the Yankees do not want him to.
"I think I kind of learned my lesson: Don't say you're tight," Youkilis said. "It's my first week here, and now I understand the terminology and what to do."
The Yankees have had their share of injuries early in camp, with right-hander Phil Hughes (back spasms) and outfielder Curtis Granderson (fractured right forearm) already sidelined, but Youkilis said that he shouldn't be lumped into that group.
"I got up today and was moving around fine," Youkilis said. "It's one of those things where, I think after I swung yesterday and running and all that, it was hot and I got a little dehydrated. When I got water in me, I was fine.
"Being a month away from games and all that, they just wanted to take it precautionary. I wanted to play today and was perfectly fine to play and didn't feel like there was a risk."
Addison Maruszak replaced Youkilis in the lineup at third base for New York's Grapefruit League exhibition against the Phillies in Clearwater, Fla.
Bryan Hoch is a reporter for MLB.com. Follow him on Twitter @bryanhoch and read his MLBlog, Bombers Beat. This story was not subject to the approval of Major League Baseball or its clubs.