Phil Hughes has a stress fracture in one of his ribs, and the New York Yankees' pitcher is expected to be sidelined for at least two months.

The news comes at an inopportune time for the injury-depleted Yankees, also missing three-time MVP Alex Rodriguez, All-Star catcher Jorge Posada and reliever Brian Bruney.

"I say no on crisis mode," general manager Brian Cashman said. "I say this is what every team that wants to get to the promised land has to deal with at one point or another, and deal with it. And if you can't, you're not championship-worthy."

Hughes, placed on the 15-day disabled list Thursday, had tests that revealed a stress fracture in the ninth rib on his right side. He will be shut down for four weeks and then re-evaluated. Cashman said the team probably can't expect the 21-year-old right-hander back before July.

Hughes is 0-4 with a 9.00 ERA in six outings this year, an alarming start for a touted youngster who was expected to be a key member of New York's rotation.

"His fastball command has been uncommonly off. Now we get an idea why," Cashman said.

Still, Hughes refused to offer the injury as an explanation or excuse for his struggles.

"I really don't think it was an issue in my performance," he said. "Subconsciously, I may have been doing something different or whatever. But it's still something that I want to work out as far as performing well when I get back."

When the Yankees put Hughes on the DL, they initially said he had a strained right oblique muscle. Both he and the team were surprised to receive a more serious prognosis.

"At least for me, I was in disbelief," Hughes said. "I was expecting to get the results of the MRI and have some small muscle strain or something like that. For it to be this, especially with the way things are going pitching-wise and everything else, it's just not a fun time right now."

Hughes said he has "no idea" how he got hurt. He first felt a little discomfort the morning after a two-inning start at Chicago last week, when he didn't come out for the third because of a rain delay.

He was tagged for six runs and eight hits in 3 2-3 innings of a 6-4 loss to Detroit on Tuesday night.

"It could have been around for a while and it was just so minor that I didn't know it. Or it could have been something that happened overnight. There's no way of knowing," Hughes said. "There wasn't like one specific pitch, like I said, where I felt it. It was just one of those things. I woke up one morning and there was a little discomfort, but nothing major. And then after last night there was significantly more discomfort."

Right-hander Darrell Rasner, 4-0 with a 0.87 ERA in five starts at Triple-A Scranton/Wilkes-Barre, will start in Hughes's spot Sunday against Seattle.

"Disappointed more than anything. But at least I have an answer for what was going on in there," Hughes said. "I was worried about what it was."

Rodriguez is on the 15-day DL with a strained right quadriceps. The Yankees were waiting for additional opinions on Posada's ailing throwing shoulder before determining whether he needs surgery.

New York manager Joe Girardi said before Thursday night's series finale against the Tigers that Posada is doing strengthening exercises for his shoulder and won't throw for two weeks.

Hughes was working on a no-hitter in his second major league start last May 1 at Texas when he departed after 6 1-3 innings because of a strained left hamstring. He sprained his left ankle while rehabilitating the original injury and didn't return to the Yankees until Aug. 4. He finished the season 5-3 with a 4.46 ERA in 13 starts.

"His first two years here now in the big leagues he's suffered some setbacks," Cashman said. "But we're hoping that it's going to be a long career. If that's the case, hopefully he's getting it out of the way early."