BOSTON -- If the day at Fenway Park belonged to Jesus Montero, a kid projecting the vibe of an awestruck tourist, it was fitting the night belonged to a New York Yankee twice his age, the one Yankee forever voted most likely to decide whether a Red Sox season lives or dies.
Mariano Rivera, closing hard on his 42nd birthday, had the ball in his hand, bases loaded in the ninth, Red Sox down two runs and all of Fenway feeling that the home team was about to deliver Rivera yet another cruel reminder of his own mortality.
Adrian Gonzalez, the game's best hitter, stood at the plate. Across his epic career, Rivera had blown 14 regular-season saves against Boston, and helped turn the 2004 ALCS into the kind of nightmare Stephen King wouldn't have wished on the Yanks.
Rivera had to be nervous, right? He had to be thinking the Red Sox were going to win this series by reminding the world they have Mo's number the way Mo has everyone else's number.
"Nervous?" Rivera said at his locker after throwing on his jacket and fixing his tie knot and preparing for a short and giddy ride home.
"Nervous is not an option. If you get nervous, you will lose the game."
So no, Rivera didn't get nervous; he got even.
First he surrendered a couple of walks and a two-out hit to Marco Scutaro. Gonzalez, batting .341, could've tied it with a single, and won it with something bigger. He entered the night with three career at-bats against Rivera, none of them successful.
"I know Adrian, a great hitter," Rivera said. "But I don't back up in any situation."
Rivera had a plan, if only because he always has a plan. He opened up by working Gonzalez inside. "I knew he was bailing and he was trying to get the head out in front," Rivera said.
Gonzalez swung through strike one, fouled off two and carried a 1-2 count into the final, fateful pitch. Russell Martin asked for a cutter -- what else? -- down and away.
"We hadn't shown him that pitch yet," the catcher said.
So Rivera showed it to him, and to Martin, and to the home plate umpire, Alfonso Marquez, a 93-mph cutter that caught the edge of the strike zone. Gonzalez thought it was a ball, Marquez did not.
"We had a chance to get him away, and we did," Rivera said. "And that was that."
The big hitter on the night, Martin exploded from his crouch and pumped his fist. Rivera celebrated his 36th save of the year and the 595th of his career -- six short of Trevor Hoffman's record -- the way he celebrated his first big-league save in 1996. With dignity and grace.
"You never see him lose focus out there," Martin said, "and that's more incredible than anything. Just his ability to stay focused in tough situations."
And yes, this qualified. The Yankees and Red Sox are both heading to the playoffs, but each team treated this series as if the American League East would get only one bid to the postseason tournament.
Against all odds, Rivera was among the principal fall guys the last time the Yanks and Sox met in the tournament. Seven years ago, in Game 4 of the ALCS, Dave Roberts happened and Bill Mueller happened and then the exorcism of Babe Ruth's spirit happened.
So much has changed about the rivalry between then and now, but two things have remained the same:
• The teams still play games that last longer than the Iditarod.
• Rivera often has a dramatic role to play in those games around the stroke of midnight.
"It's wonderful," Rivera said of the tension that gripped Fenway on Thursday night and throughout the series. "That's why you play the game of baseball, because anything can happen until the last minute.
"You have to keep grounded, keep grounded, and make sure you make your pitches. At the end of the game, if you make your pitches, you'll be fine."
Rivera didn't make his pitches here in August, blowing a Sunday night save, and yet he maintained that this bases-loaded duel with Gonzalez at the end of a 4-hour, 21-minute game didn't rattle him in the least.
"You can't do it," he said.
Rivera was reminded that it's human nature to be anxious in those situations.
"That's why only a few people can do it," the greatest closer of them all responded.
Rivera has made 107 appearances against Boston. The Red Sox know him, know his cutter, know his flesh-and-bone vulnerabilities.
They respect Rivera, but don't fear him. Billy Beane, architect of the Moneyball A's, once told me this of the Yankees closer: "It was so psychological to know he was out there; you knew you weren't going to beat them. You had no chance. You knew Rivera had the sickle in hand ready to get you."
The Red Sox see no bogeyman on the mound, and I asked Rivera why. "Seventeen years," he said, "that will do it. But I don't take anything away from them."
He helped take a series away from them Thursday night, a series the Yankees needed for all sorts of mental health reasons. Rivera made the one pitch he had to make, and left Gonzalez to blame the ump.
"The only thing I have to say," the first baseman said, "is that pitch was down and I should still be hitting. [The count] should be 2-2 and you can quote me on that."
Rivera wasn't sweating it, not when he had a plane to catch. It had been a long trip and a longer day in Boston, where the Yanks unveiled their latest wonder boy, Montero, who went hitless and stranded seven runners after Brian Cashman offered this forecast by phone:
Time will tell. The kid looked around Fenway on his opening night, and realized he wasn't in Scranton or Wilkes-Barre anymore.
As for the old man on Montero's new team, Mariano Rivera, stage fright wasn't much of an issue.
The Red Sox might conquer him here or there, but they'll never unnerve him.
Ian O'Connor is the author of "The Captain: The Journey of Derek Jeter."