BOSTON -- Now this was certainly something new.

One month after the Yankees first took the wraps off Joba Chamberlain, their 21-year-old eighth-inning ace revealed his own secret weapon. They've seen the triple-digit heater and the hard-biting slider; but is the American League ready for a curveball?

"He's got a good one," pitching coach Ron Guidry said. "He hasn't thrown it a lot, because he's only been in there for maybe an inning, so we guard it. But he does have a good one."

Twice Chamberlain dropped the hammer in the eighth, making a pair of confused Red Sox look foolish. It wasn't supposed to work that way. He gets ahead in the count with 100-mph fastballs. He shows the slider if the occasion strikes. But a hook?

"They hadn't seen something like that," Chamberlain said. "This was the third time that I faced those guys. So, going into it, they kind of knew, when I get ahead, that we go to a slider. [I threw it] to give a different view of a breaking pitch."

Chamberlain's appearance on Sunday had its roots in the sixth, when starter Roger Clemens escaped a first-and-third jam. The Rocket was nearly gassed; he hadn't thrown six innings since Aug. 29, and the Yankees were happy to get that much baseball in his first start back after elbow stiffness.

Clemens pitched brilliantly. But he knew he was done.

"As he walked out, he told me to make sure I'm ready," Chamberlain said. "And when somebody [like that] says that, you make sure you're ready."

Chamberlain had already warmed up in the Fenway Park 'pen, his first time up before the Red Sox faithful. The 6-foot-2 lightning rod expected some verbal abuse.

"It actually wasn't that bad, surprisingly," Chamberlain said. "I thought it would be worse. But you know, I just went about my business, and I really didn't hear much."

While warming up, he spun the curveball. Felt good enough to use it, even though he'd only done so a couple of times -- "probably three or four," he said -- this season.

But even after he'd entered the game and yielded a leadoff double to Eric Hinske in the seventh, Chamberlain kept it under wraps.

"If you're going to go in there for an inning," Guidry said, "you don't need to show it. If you go in there for two innings, you can show something else."

Chamberlain got out of the seventh without trouble, snapping Jacoby Ellsbury's bat with a slider after staying high and tight with a couple of heat-seeking fastballs. Still no curve.

Yankees Coverage
Jeter's late homer lifts Yanks
Yanks gear up for lesser opponents
Chamberlain springs curve on Sox
Notes: Peace of mind for Posada

Red Sox Coverage
Schilling's gem ends with loss
Bauman: Game mirrors Classic duel
Sox don't take lead for granted
Notes: Matsuzaka pushed back
Season Series
Yankees win 10-8
• 9/16: Yankees 4, Red Sox 3
• 9/15: Red Sox 10,Yankees 1
• 9/14: Yankees 8, Red Sox 7
Previous season series
2006: Yankees 11, Red Sox 8
2005: Yankees 10, Red Sox 9
2004: Red Sox 11, Yankees 8

The Red Sox sent Dustin Pedroia to lead off the eighth. Chamberlain pumped in two fastballs to get ahead, then ran the count to 2-2 with a slider away. With the fifth pitch, he froze Pedroia with the curveball.

Whose idea?

"Ask him," manager Joe Torre said. "I have no clue. We had nothing to do with it. The kid's got a lot of guts. Ask him that question."

"It was his," Guidry said.

But, Guidry added, he had worked with Chamberlain on the curve previously during side sessions. As a starter at Nebraska and in the Minors, Chamberlain commanded a broader repertoire of off-speed stuff.

"I've been a two-pitch guy for the beginning of the season, you know, going in as a reliever," Chamberlain said. "And then to be able to show a pitch I can throw for a strike, other than a slider ... it's just going to help me in situations [like] that."

"He's always trying to figure out something to get you off the fastball-slider," Torre said, "because they're both hard."

Meanwhile, the eighth inning was notable for another reason. With two outs, Mike Lowell cracked a 98-mph fastball at the letters, arcing a high home run into the Green Monster seats. Chamberlain took the earned run, his first in 17 2/3 Major League innings. The owner of a newly commemorated 0.50 ERA tasted, remarkably, his first big league failure.

"I'm not going to throw my life scoreless," Chamberlain said. "So you've got to take it with a grain of salt. That game's still 4-2."

You want poise? How about earning a mound visit from the pitching coach, only to be the one giving the reassuring pat?

"When I see Joba pat Gator [Guidry] on the shoulder," said Torre, "I say, 'Well, I guess he's all right.'"

Torre laughed.

"Yeah, he's pretty special," he said.

Up walked J.D. Drew with two outs. Fastball, fastball, fastball, fastball -- all at least 97 mph. Chamberlain looked in, stood tall, unwound, and delivered a curveball. Drew froze, taking a called strike three.

With that, Chamberlain delivered a 4-2 lead to Mariano Rivera, conjuring up for Yankees fans, on a chilly night in Boston, a hint of what may lie next.

"Joba's been awesome," Johnny Damon said. "Unfortunately he gave up a run, but better now than later."