Injury bug biting senior Bombers

Jorge Posada was on his way to a hospital, keeping an appointment with an MRI tube.

Curtis Granderson, wherever he was, was hobbling around on one good leg.

Javier Vazquez, bumped from his next start, was nursing a bruised psyche.

The news couldn't possibly get any worse for the Yankees. Or could it?

Well, here it was, the top of the ninth inning at Yankee Stadium, the home team holding a three-run lead over the Baltimore Orioles, a save situation, and when the bullpen door swung open, Joba Chamberlain came running out.

The ending was a happy one -- Chamberlain pitched a nearly spotless ninth to preserve the 4-1 victory -- but the big question remained:

Where's Mo?

The answer was, right where he belonged, in the bullpen, although unavailable due to what he termed "tightness" in his left side and manager Joe Girardi called "stiffness in his flank."

But any way you sliced it, it came down to the same thing -- Mariano Rivera, the Yankees' closer extraordinaire, probably the key player in their 14-year run to five world championships, was unavailable Monday night and probably will be unavailable Tuesday night as well.

"I'm not worried at all," a cheerful Rivera said in the postgame clubhouse. "We won. What do I got to worry about?"

Indeed. The news on Posada, similarly, came back encouraging -- around 11 p.m., the Yankees announced the MRI revealed "a mild strain" of the right calf. Instead of joining Granderson on the disabled list, Posada's status was said to be day to day.

Good news for today, but what about for tomorrow? If nothing else, it served to remind you of the one big fear about this club coming into the season, namely, the number of key players who are aging, and consequently, leading candidates to miss significant portions of the season to injury.

The Yankees enjoyed a largely injury-free trip last season, a huge boost to their successful bid for their first world championship in nearly a decade. Team officials were aware of that, acknowledged it -- and hoped and prayed their luck would hold out again this season.

Now, little more than a month into their title defense, they are wondering if such an event-free two-year run is even possible.

"I think any time you see guys starting to get nicked up, it's a concern," Girardi said. "You know, we've talked about the importance of giving guys days off, because we have some ... I don't want to insult them, but ... older players on this club. And we have to be careful. We have to be smart about spelling them when they need a spell, and it's not always when they think they need it. Sometimes, we have to make tough evaluations."

Apparently, Rivera has not been available since Friday night, when he closed out the 6-4 win over the White Sox but felt the sensation -- tightness, stiffness, pain, whatever you want to call it -- in the left side of his back.

"It didn't affect me at all," Rivera said. "I finished pitching the game, but I felt it, you know? I can't even describe it. I didn't feel any pop or pull or anything like that. But it's like, when I sneeze, I feel it."

And when Rivera sneezes, the whole Yankees team catches cold. Same goes for Posada, an indispensable part of the club not just because he's a member of the legendary core four, but because he's by far the best bat they can produce at catcher right now. Francisco Cervelli is adequate, but after him, they don't even have another catcher on the 40-man roster to turn to in an emergency.

Alex Rodriguez's flirtation with the bench on Sunday raised another flag, especially since he is a 34-year-old player coming off major hip surgery a year ago, and even more especially since neither he, his manager nor his GM could quite get their stories straight on why, exactly, he was given the day off.

Girardi said it was a scheduled rest day; Brian Cashman said there was a muscle-related issue he felt while running the bases; A-Rod muttered some vagaries about a cramp he was unable to pinpoint the location of. Other Yankee sources have been cited as locating A-Rod's problem in the area behind his right knee.

Whatever the real story is, his loss would be a crushing blow to this lineup, even with him hitting just .258 with a mere two home runs.

"I don't think we're going to get into a state of playing 30, 40 games in a row, although I would like to," Rodriguez said before the game. "I think we're all learning as we go along."

Mastering the art of knowing when to hit and when to sit with players in their mid-to-upper 30s is going to be one of Girardi's toughest managerial tasks this season. "This is a real concern of mine, because we still have a long ways to go," he said. "I'd rather lose a guy for a day or two than wind up losing him for two weeks or a month."

And with it, perhaps a season.

Game notes

CC Sabathia earned his fourth win of the season with a gutty performance, throwing eight innings and giving up one run despite having nowhere near his best stuff. He was in numerous three-ball counts but got out of trouble with the help of two double plays and 15 ground-ball outs. He also got into a beef with home-plate umpire Bill Hohn over the strike zone, which seemed to shrink when he was on the mound.

"A couple of years ago, I wouldn't have been able to control my emotions," Sabathia said of the seventh-inning incident, in which Hohn took a few steps toward the mound while letting loose with some choice words Sabathia said he could not remember. "Earlier in my career I would have been all over the place, but tonight I was able to relax and regain my focus." ... Randy Winn, who hit what turned out to be the game-winning homer, a three-run blast into the Yankees' bullpen off Jeremy Guthrie (0-4), hadn't hit a home run since April 25 of last year, a stretch of 491 at-bats. Asked if he could remember it, Winn said, "No. Yes. Maybe." Turns out he could -- it was off Arizona's Max Scherzer when Winn was a San Francisco Giant. "I really don't hit too many of them," he said. "So they're kind of hard to forget." ... Nick Swisher continued his hot hitting, going 3-for-3 with a double and raising his average to .307.

Wallace Matthews covers the Yankees for ESPNNewYork.com. Follow him on Twitter.