Alex Cora of the Red Sox delivers what proved to be the game-winning single in the eighth inning of last night’s series opener against the Yankees at Fenway Park.

The Providence Journal / Bob Breidenbach

BOSTON — Never mind that Yankee manager Joe Torre brought in ace and aging closer Mariano Rivera for more than a one-inning save opportunity, as he steadfastly has been saying he wouldn’t be doing this season.

He held to that philosophy — until last night, the first Yankee-Red Sox matchup of the season.

Then with the game in the balance in the eighth inning, he called on Rivera.

It’s something Boston manager Terry Francona has been doing with Jonathan Papelbon.

There can be debate as to whether Torre made the right move in terms of Rivera’s health for the full season. But there is no debate that New York’s brain trust, not to mention the players and the Yankee fans, has to be concerned that maybe, just maybe, this is the year that the right-hander finally becomes less dominant and dependable.

Rivera blew last night’s save — big time.

The score was 6-4, New York, with Boston runners at first and second and one out in the eighth. Three batters later — Jason Varitek single, Coco Crisp triple, Alex Cora soft single a la Luis Gonzalez for the Diamondbacks in winning the 2001 World Series — the Sox were ahead, 7-6.

It was only the second time Rivera had pitched in six days. And he has blown saves each time. He was victimized for a walk-off three-run homer by Oakland’s light-hitting Marco Scutaro in Oakland last Sunday.

Last night was worse, a seemingly in-the-back-pocket win against the bitter division rivals turned into an excruciating loss.

His once-devastating cutter did not have nearly its customary bite last night.

Worst of all for the Yanks, there are major doubts about the once-invincible Mariano Rivera, who has been shown to be mortal several times by the Red Sox since 2003.

Not up to challenge

The challenge fell to Red Sox ace Curt Schilling to slow down Alex Rodriguez last night and set a tone for the weekend’s series with New York.

The Yankee third baseman was on a torrid home-run-hitting pace, having clubbed 10, notably a pair of walk-off blasts, a grand slam that toasted Baltimore and a three-run shot that shocked Cleveland only one day earlier.

Schilling loves such challenges. He thrives on such challenges.

But on this night, no matter what Schilling tried, from pitch selection to pitch patterns, it didn’t work at all.

Oh, maybe once. A-Rod lined out to the fence in center field his first time up. But his second and third times, A-Rod touched them all.

He pulled a home run to left field leading off the fourth. And he snapped a tie with a three-run homer into the Sox’ bullpen in the fifth.

Schilling tried mixing fastballs and changeups in the first at-bat, keeping the ball away. He reached back and threw a 93-mph fastball to the outside corner, about knee-high, and Rodriguez laced it to center, but for a long out.

In the fourth, Schilling got A-Rod to swing and miss a 90-mph heater on the outside corner, knee-high on his first pitch. Catcher Jason Varitek called for a fastball on the next pitch and set up inside.

But the fastball, at 92 mph, was in the same spot as the first one. Rodriguez stayed balanced and yanked it into the Monster seats.

In the fifth, a fastball (92, called strike) and a splitter (82, down and away for a ball) had the count even. Varitek set up outside for a fastball, but it sailed up and in at 94 (Schilling’s top reading of the night), and Rodriguez swung and missed.

Varitek went out to talk to Schilling. He set up outside, off the plate, for the 1-and-2 pitch. Schilling threw a 92-mph fastball off the plate — it likely would have been called a ball had A-Rod taken it — but Rodriguez, again staying balanced on his back leg, launched it into the Sox’ bullpen in right-center for his second homer of the game and 12th of the season.

Interestingly, manager Terry Francona was going to let Schilling face A-Rod again in the seventh if he had come up. Rodriguez was due up fourth in the inning, and Francona had only a left-hander (J.C. Romero) warming up in the bullpen, for Jason Giambi, the fifth scheduled hitter of the inning had it gone that long.

But Schilling mowed down the Yanks in order in the inning, his last.

Snyder was a key

It didn’t seem big at the time to most people.

But Kyle Snyder may have saved the game for Boston in the eighth.

He came in with Boston trailing, 6-2. There were runners at first and third and one out, a seemingly gimme insurance run at third.

But Snyder stranded him, leaving the Sox down by four heading into the eighth, and making their five-run rally good enough for the pulsating victory.

Another move that didn’t seem big at the time. Torre decided to pull Jason Giambi for a pinch runner after his single had put New York on top, 6-2, in the eighth. As a result, it was rookie Kevin Thompson who represented the Yanks’ last hope with two out and a man on in the ninth against Hideki Okajima.

Thompson fanned, ending the game.

Crossed signals

A seemingly botched signal cost the Red Sox a baserunner in the fourth inning.

J.D. Drew was on first base with one out and Mike Lowell was at the plate. The Yankee pitcher was Andy Pettitte, a left-hander with one of the best pickoff moves in the game.

On the 1-and-0 pitch to Lowell, Drew waited to make sure Pettitte was throwing home before taking off on what he thought was a hit-and-run play. Drew was looking back to the plate as he was taking off, checking to see if Lowell had made contact.

But Lowell took the pitch, and Drew was out easily at second base, gunned down by catcher Wil Nieves.

Still, the Sox wound up scoring two runs in the inning. Lowell singled off the wall and Jason Varitek homered into Boston’s bullpen.

Three long outs

Apparently, the Yankees have warning-track power.

At least they did in the second inning.

Alex Rodriguez flied to the warning track in dead center. Jason Giambi flied to the warning track in left. And Jorge Posada flied to the warning track in center, near the 379-foot marker.

For the record, that was roughly 1,115 feet worth of outs. Clearly, Curt Schilling was popping up the Yankees that inning.

Right man for job

The Yanks are known as the Bronx Bombers, a nickname pinned on the franchise long ago.

And they still have plenty of power in their lineup.

But with the right man up in the right situation, manager Joe Torre isn’t afraid to play some “small ball.”

That perfect scenario cropped up in the third inning. Singles by Robinson Cano and Melky Cabrera put runners at first and second with none out, bringing to the plate the right man at the right time for the sacrifice bunt.

That man is Doug Mientkiewicz, the former first baseman on the Sox’ World Series-winning team in 2004, who bats ninth in New York’s order. Mientkiewicz was called on to bunt, and he did the job on the first pitch from Schilling, moving the runners over for his second sacrifice bunt of the season.

The Yanks got one run out of it, on Johnny Damon’s groundout, for a 1-0 lead.

Heads-up umpires

Third-base umpire Hunter Wendelstedt and first-base umpire Bob Davidson did a nice job of hustling to get into position to make the correct calls on a pair of low liners.

Wendelstedt was right on it when Red Sox left fielder Manny Ramirez made a sliding attempt to catch Cano’s sinking liner in the second. Ramirez short-hopped the ball, and the umpire quickly ruled it a trapped ball.

Davidson did the same thing on J.D. Drew’s similar base hit in the fourth, when Yankee right fielder Bobby Abreu trapped his sinking shot.

Davidson also was right on it when Mientkiewicz had to come off the bag a few inches to catch a throw from A-Rod, with Coco Crisp safe at first on an infield single in the seventh.

skrasner@projo.com