BOSTON — Call it a reprieve for Alex Rodriguez and the rest of the New York Yankees.

After failing to knock in critical runs in two at-bats earlier in the game, Rodriguez capped off a wild weekend at Fenway Park by nailing an 0-2 fastball from Jonathan Papelbon into the Red Sox bullpen to deliver a 6-5 Yankee victory.

Rodriguez’ ninth-inning heroics came just in time for a team in dire straights. The Yankees leave Boston trailing by 12½ games in the American League East but after taking two of three from the Sox (4 of 6 in two series over the last two weeks), Rodriguez and his teammates are far from ready to wave the white flag in the playoff picture.

“It was a big win for us, but it’s important what we do after this,” said Rodriguez. “Today was good but we have to back it up.”

The Yankees needed this win badly. New York built a 4-0 lead off Boston ace Josh Beckett with three of the runs coming in the top of the fifth. The key play in the rally was a hard chop to third by Rodriguez that Mike Lowell threw away. Melky Cabrera and Derek Jeter scored on the play. One batter later, Jorge Posada singled in Bobby Abreu and the Yanks appeared in control with a four-run lead.

The edge didn’t last long, however. Just as they have done most of the season, the Yanks handed a ballgame back to their opponents in dizzying fashion. This time veteran pitcher Andy Pettitte let the Red Sox take control in the bottom of the fifth. Jason Varitek, Wily Mo Pena and Coco Crisp all singled to load the bases. After a strikeout, Dustin Pedroia stroked a double high off the Wall in left-center to make it 4-3. David Ortiz singled in the tying run and the Sox went ahead, 5-4, on a Kevin Youkilis sacrifice fly to center.

The Yankees kept at it and had a few chances to jump back ahead. Rodriguez came up in the seventh inning with runners on first and third with one out but popped out to short. A fly ball out by Posada ended the threat.

In the eighth, New York struck and scored the tying run off Hideki Okajima. Hideki Matsui led off with a single and scored when Robinson Cano crushed a triple to deep center. Unlike too many nights this season, the Yankee bullpen help an opponent at bay. Luis Vizcaino, Kyle Farnsworth and Brian Bruney all combined to keep the Red Sox scoreless.

With the game still tied at 5-5, Boston countered with Papelbon in the ninth. With rain picking up by the minute, Papelbon retired the first two hitters with his crackling fastball. Then he jumped ahead to A-Rod with two strikes but the next pitch was lined hard into the Boston bullpen for his 20th home run of the season.

Rodriguez was the focus of Red Sox fans all weekend. They serenaded him with chants of “A-Rod, A-Rod,” and made mention of a report in the New York newspapers last week of a relationship he has with a professional stripper.

Every win is critical for the Yankees right now. Before the game, the team even acknowledged that former Red Sox outfielder Johnny Damon is working on trading in his glove for a first baseman’s mitt. In 12 major league season, Damon has played one inning at first. The last time he regularly roamed the position? Try Little League.

“As an outfielder, (my arm) is very below average. As a first baseman, it’s just below average,” Damon said before taking some grounders under the watchful eye of one of the all-time greats at the position, Don Mattingly.

Damon was smiling as he spoke those condescending words but the Yankees’ plight is no laughing matter. Manager Joe Torre is juggling his lineup yet again these days thanks to plenty of ill-timed injuries. The latest is the broken wrist suffered by Doug Mientkiewicz Saturday when he was involved in two dust-up plays, the second of which left him dazed after getting blind-sided by Mike Lowell’s thigh in a tight play near the first base bag.

Mientkiewicz is a valued reserve, playing only because Jason Giambi (partial tear of plantar fascia in left foot, out 3 weeks) beat him to the disabled list. Josh Phelps, a three-year veteran with a good glove but little offensive resume, started at first last night for the Yanks but he’s clearly not an everyday solution.

“We talked about not only taking ground balls at first base but fly balls in left and right field. Johnny said ‘fine,’ and that’s what he’s been doing,” said Torre. “I think it could be an option, probably more so now with (Mientkiewicz) down. At this point in time with the people we have available to us, he can be an option. I don’t see another guy over him.”

The happy-go-lucky Damon seems to welcome the challenge.

“I’m okay to be thrown into the fire,” said Damon, who joined the long list of injured Yanks a few weeks ago with sore calves. “Right now I’m a DH/outfielder but I need to be ready to play first base, too. That’s fine with me with the current situation we’re in.”

It’s a situation that may still border on dire but was made just a bit more comfortable last night thanks to a timely bomb from Rodriguez in the ninth inning.

“Your battling for your life at that point,” said Rodriguez. “The last thing on my mind is to hit a home run. The last thing.”

kmcnamar@projo.com