Boston ? The bullpen blew another one.

The reliable relievers who carried the New York Yankees all season are coming apart at the most important moment.

Mariano Rivera must be tired by now. Tom Gordon is struggling. Paul Quantrill is hurt. And the Yankees are halfway to the biggest collapse in postseason history.

“It’s a heavyweight battle,” Gordon said. “Right now we probably just need to back off a little bit and make it more fun for us. This is what it’s all about.”

This time, it was Gordon who failed to protect a late lead, and the Boston Red Sox saved their season again by rallying for a 5-4, 14-inning victory Monday night in Game 5 of the AL championship series.

“That’s why you’ve got to play the whole game. Close doesn’t count,” Derek Jeter said.

Much of the blame falls on New York’s star-studded lineup, too. Alex Rodriguez and Hideki Matsui had opportunities to wrap it up but couldn’t come through in the clutch. That’s been a theme for the Yankees all season, and it’s costing them in October.

That left the game in the shaky hands of Esteban Loaiza, who struggled so much after coming over from the Chicago White Sox that he lost his spot in the rotation.

Loaiza delivered a fine effort for three innings, but he walked Johnny Damon in the 14th and gave up a game-winning single to David Ortiz, also the hero the night before. This one ended the longest game in postseason history at 5 hours, 49 minutes.

“I guess it doesn’t get better than that,” Loaiza said. “It was a great pitch, a broken bat, and it floated over second base.”

With all those championships and a seemingly insurmountable 3-0 lead, it’s the Yankees who appear to be crumbling under pressure. They have lost consecutive extra-inning games for the first time in their postseason history.

On the brink of a sweep less than 24 hours before, they’ve wasted two chances to put away their rivals. The Red Sox are gaining confidence, and New York can’t find anyone to get those crucial outs in the eighth and ninth.

Nobody expected this to be the problem in the playoffs. Rivera always had been dominant in October, and he was coming off perhaps his best season. But the All-Star closer let a ninth-inning lead slip away Sunday night, and Gordon put him in a bind in Game 5.

“I don’t get tired at all. We’re in the playoffs, trying to win a game to go to the World Series. There’s no time for rest right now,” Rivera said.