NEW YORK -- All good things must come to an end, and sometime in the not-too-distant future, the Yankees' "Core Four" of star veteran players will be no more.

Athletes, unlike people in most other endeavors, are undermined by a sudden decline at a relatively young age.

And so we are seeing that this year among the four: Derek Jeter is sputtering along at about 40 points below his .308 lifetime average, Mariano Rivera is suddenly a little more fallible, Andy Pettitte missed almost the entire second half of the season because of a groin injury and Jorge Posada has been just plain beaten up.

"The injuries are certainly tougher to deal with as you get older," Posada said before the Yankees played the Rays at Yankee Stadium on Thursday night. "The funniest thing is, when you get up in the morning, you don't know how you're body is going to feel. Some days are better than others. It's such a long season."

No wonder. Posada is still catching quasi-regularly at 39; Rivera is still closing games at 40; the Captain, 36, has defied all odds maintaining his All-Star status at short; and the left-handed Pettitte, at 38, was having one of his best seasons until he hurt himself after the All-Star break.

Let's put these accomplishments into perspective. Catcher Yogi Berra, closer Rich "Goose" Gossage, shortstop Phil Rizzuto and left-hander Whitey Ford -- all Yankees Hall of Famers -- were spent at comparable ages.

"I think they've done very well this season," said manager Joe Girardi, whose career as a catcher was over at 38. "We try to be smart with all these guys so they make it through the season, because we know how important they are down the road."

Girardi, of course, is viewing this in terms of this season and the playoffs that follow. But how long that winding road will be is really the question.

The Yankees have some hard decisions this offseason when it comes to re-signing three of these players. Posada has one year left on his contract, but Jeter, Rivera and Pettitte are all free agents. Jeter is only 85 hits shy of becoming the first career Yankee to amass 3,000. Rivera is 42 saves behind Trevor Hoffman's record 600. Neither is going anywhere.

Pettitte will have to decide whether he wants to continue pitching or retire -- a decision he has pondered for the past few offseasons.

Hal Steinbrenner, who replaced his late father as the team's principal owner, reiterated the other night that the Yankees want these cogs in the machine back, but at what cost -- in both price and contract length? Steinbrenner said that he would certainly take into consideration leadership qualities and value to the team outside of sliding statistical measures.

"I try to remain objective," Steinbrenner said, "but I'm not going to do anything that's going to place the franchise in any long-term financial jeopardy."

Which undoubtedly means that the 10-year, $189 million contract Jeter signed at the age of 26 won't be matched, certainly not in length. It also means that there may be some hard negotiations in the months ahead.

Rivera has also traveled far down the closer's road. Hoffman, at 42, went out like a light bulb this season in Milwaukee, saving only nine games.

"It's definitely tougher now at this age," said Rivera, whose three-year, $45 million deal was signed after the 2007 season. "Even as a writer, you can't tell me that it isn't a tougher job to do today than when you were 30 years old. Every year is a little different."

The Yankees have done the nearly impossible in this era of free agency by keeping the Core Four virtually intact since 1996, save for Pettitte's three years with the Astros (2004-06). The four have contributed to five World Series titles and seven American League pennants.

But eras end, as other great Yankees discovered. Rizzuto was unceremoniously released on Old Timers' Day in 1956. Berra was hired as the team's manager in 1964 and dismissed after the Yankees lost to the Cardinals in that World Series. Reggie Jackson was banished to free agency after the Yanks lost the 1981 World Series to the Dodgers.

Judging by their statements on Thursday, neither Rivera, Posada nor Jeter is ready to hang it up.

"I want to play as long as God wants me to play," Rivera said. "One thing I'll tell you is that I want to continue to do my job at the same level I'm used to. If I can't do that, then I'm ready to go."

"I'm just thinking about today," said Posada, who is catching more games at his age than any backstop in recent baseball history save Bob Boone and Carlton Fisk. "I still have one more year, and when I finish that year, you can ask me that question. But I'm still having fun."

Jeter, the youngest of the quartet, seems to be in a bit more denial about skills that naturally diminish with age.

Asked how long he still wanted to play, Jeter said, "I'm not going to answer that."

How does he feel physically? "Good," he said.

Any difference going through the long season now than when he was younger? "No."

Told that Rivera and Posada said it was tougher on them, Jeter responded, "That's them. I'm good."

So are the Core Four. At least for now.