BOSTON - Alex Rodriguez heard the jeers of the fans, then shut them up.

Mocked all weekend by the Red Sox passionate backers, A-Rod hit a tiebreaking home run in the ninth inning against the star closer for the Yankees’ biggest rival.

“I heard some, but it’s always in good fun,” he said after his solo shot through the rain off Jonathan Papelbon gave New York a 6-5 win Sunday night and the rubber game of the series. “I think the Boston fan always has a lot of fun and I appreciate that. It’s not a big deal.”

Yankees manager Joe Torre thinks it may have been a bigger deal than Rodriguez let on.

“It’s got to take some of the sting out of it, I would think,” Torre said. “Obviously, when you’re dealing with a personal situation, it’s more than just a game at that point.”

On Friday night, many Red Sox fans held masks picturing a blond-haired woman in front of their faces — a reference to photos published last week of the married Rodriguez with a blonde woman in Toronto.

On Sunday night, they yelled loudly as he settled under a popup four days after he said something as he passed between — and angered — two Blue Jays infielders, causing one of them to back off and let the ball drop.

And in the ninth, he fell behind 0-2 to Papelbon (0-1), who had easily retired the first two batters. But A-Rod lined the next pitch into the Red Sox bullpen in right-center, giving him 20 homers for the 12th straight season.

“I’m not trying to do too much,” he said. “The last thing on my mind is to hit a home run.”

He continued his outstanding ninth-inning hitting, improving to 7-for-15 with four homers and 11 RBIs in the ninth inning this season.

“Next time I’ve got to get him to chase a pitch outside the (strike) zone,” Papelbon said.

The Yankees’ comeback from a 5-4 deficit kept them out of last place in the AL East and left them 12½ games behind the first-place Red Sox.

“It’s important what we do after this,” Rodriguez said before the Yankees headed to Chicago to face the White Sox. “We were in a must situation where we needed to win this series against a good team. (Now) we’ve got to back it up.”

Brian Bruney (2-1) got the win and Mariano Rivera earned his fifth save — just his second since May 3. David Ortiz opened the ninth with a drive to deep right that was caught on the warning track. He has not homered in 19 games and 69 at-bats, his longest drought in five seasons with the Red Sox.

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“He keeps swinging, I’m going at him,” Rivera said. “He’s just got to hit the ball out of the park. That’s the way I pitch.”

Boston starter Josh Beckett, trying to improve to 9-0, allowed four runs and eight hits in 6 1-3 innings.

“I felt like I had good stuff,” he said, but “I had a lineup full of guys over there that take a lot of pitches.”

The Yankees tied it 5-all in the eighth after Boston went ahead 5-4 with five runs in the fifth.

Hideki Matsui led off the eighth with a single against Hideki Okajima and scored the tying run on Robinson Cano’s triple. Cano was stranded at third.

Yankees starter Andy Pettitte had allowed just two singles and was leading 4-0 heading into the bottom of the fifth but left with lower back pain in that inning. He doesn’t expect to miss his next start.

The Red Sox loaded the bases on singles by Jason Varitek, Wily Mo Pena and Coco Crisp. Pettitte then struck out Julio Lugo on a 3-2 pitch but grimaced as he threw the 89 mph fastball.

“I knew something was a little tight back there and that was a pitch I needed to throw everything I had behind it,” said Pettitte, who first felt the stiffness in the third inning.

Torre and trainer Gene Monahan rushed to the mound after Lugo struck out and Pettitte stayed in the game — but not for long. He threw just three more pitches.

On a 1-0 count, Dustin Pedroia cleared the bases with a three-run double off the left-center wall into a stiff wind.