Suddenly, Chamberlain was proving just why some had been forecasting him to be the Yankees' answer to an ace-style pitcher like Boston's Josh Beckett. Beckett took the loss, as Chamberlain made the decision to move him to the rotation in-season look like a stroke of genius.
"This is what makes you better," said Chamberlain, who allowed three hits and walked one. "This is why you play the game. You understand it's going to be a tough game and this is the way it's going to be. You can't break."
With no margin for error and protecting a one-run lead, Chamberlain retired the final 10 batters he faced. Still on a closely guarded pitch count, Chamberlain was pulled after the seventh, throwing 103 pitches, 69 for strikes.
"He seems to get stronger as the game goes on," said Yankees manager Joe Girardi. "The first two innings, he didn't really find his groove, but after that, he seemed to really get going."
Spectacular defense helped Chamberlain through the early innings. In the second, Melky Cabrera made a diving stab of J.D. Drew's sinking liner in center.
That was followed by Robinson Cano backhanding a tricky grounder off the bat of Jed Lowrie, flipping to Derek Jeter and starting an inning-ending double play.
"Unbelievable," Girardi said of Cano's gem. "The double play and the catch by Melky, just great defense. Probably saved a run, those couple of plays."
And there was yet another tense Chamberlain moment with Boston first baseman Kevin Youkilis. The righty buzzed Youkilis up and in with a fastball in the seventh inning. Both teams were warned after the pitch, which hit Youkilis' bat for a foul ball.
"I'm trying to get a win and it's what you have to do," Chamberlain said. "It's a 2-0 count and the game's 1-0, you think I want to lose the lead and put the lead runner on with those guys behind him? No shot."
Yankees closer Mariano Rivera converted his 26th straight save by recording the final five outs, including working out of a first-and-second jam in the eighth. Rivera struck out Jacoby Ellsbury before getting Dustin Pedroia on a comebacker to the mound.
Alex Rodriguez and Bobby Abreu each had two hits to lead New York. The pair started a two-out rally in the third inning. After Abreu and Rodriguez singled off Beckett, Giambi singled to short with the infield shift on, allowing Abreu to cross the plate.
Beckett was the hard-luck loser, allowing nine hits and just one run while striking out six and walking one in his seven innings, while David Ortiz singled once in four at-bats in his return from a eight-week absence due to a sore left wrist.
The Red Sox would go on to secure the American League Wild Card as New York's season ended with their first miss at the playoffs in 13 years. But on that summer evening at the Fens, the Yankees had a very big reason to feel confident about their future.
"Every game is big at this point, and today, Joba deserves all the credit," said Jeter.