New York Yankees' CC Sabathia pitches in the first inning...

New York Yankees' CC Sabathia pitches in the first inning of a baseball game against the Boston Red Sox. (Aug. 6, 2011) Credit: AP

BOSTON - Be afraid, Yankees fans. Be very afraid.

It's not just that the Red Sox beat the Yankees, 3-2, in 10 innings on Sunday night. It's not just that Boston has a one-game lead in the AL East. It's not just that the Red Sox have beaten the Yankees 10 times in 12 meetings this season, clinching the division tiebreaker should the teams end up tied at season's end.

No, what should keep Yankees fans up at night is that the Red Sox are not afraid of CC Sabathia or Mariano Rivera. If the teams meet in the American League Championship Series, how are the Yankees going to win if their ace and their closer are mere mortals -- or less?

It was Rivera who gave up the tying run in the ninth inning on Sunday night. It's hardly a surprise when he blows a save against the Red Sox -- the greatest closer of all time has done it 14 times in the regular season and twice in the playoffs.

The intimidation factor hasn't been there since the pinstriped debacle that was the 2004 ALCS, when Rivera blew two potential series-clinching saves. Red Sox fans still cheer Rivera when he trots in from the bullpen, as they did on Sunday night when he was called on to protect a 2-1 lead and give the Yankees sole possession of first place in the AL East.

Instead, pesky Marco Scutaro led off with a double off the Green Monster. Jacoby Ellsbury bunted him to third and Dustin Pedroia tied the game with a sacrifice fly to left. Quick, efficient. Not painless. Not for the Yankees.

Phil Hughes gave up the winning run in the 10th on Josh Reddick's single, but it was Rivera who said, "It's a loss, and the only one to blame is myself."

Boston.com columnist Tony Massarotti crunched the numbers: Since 1997, Rivera is 58-for-74 in regular-season and postseason save opportunities against the Red Sox. That's a save percentage of .784. Rivera's save percentage against the rest of baseball over that span is .904.

The Red Sox are not the rest of baseball.

"Any time you see Mo in the game, it's not good news," Red Sox manager Terry Francona said. "But every once in a while, you've got to make a chip. That was exciting."

And what of Sabathia? Pedroia wondered if Boston's success against him is "luck," but there has to be more to it than that.

When Sabathia was the Indians' ace, he went 0-2 with a 10.45 ERA vs. Boston in the 2007 ALCS. This season, he is 0-4 with a 7.20 ERA against the Red Sox after he took a pounding on Saturday. He's 16-2, 2.11 vs. the rest of baseball.

Again, the Red Sox are not the rest of baseball. They are the Yankees' biggest rivals. Losing two of three at Fenway is a small body blow for the Yankees - easy to shake off during Monday's off-day, harder to dismiss if the teams meet again in October.

There's a long way to go before an ALCS matchup, of course. Texas, last year's AL World Series team, appears to be just as formidable as in 2010, and the Angels are lurking as well. Detroit has Justin Verlander, and who would want to face him twice in a five-game first-round series?

So there's no guarantee the Yankees and Red Sox will even meet in the second round. It hasn't happened since 2004. But if it happens this season, the Red Sox will know they can beat Sabathia and Rivera. Because they keep on doing it.

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