NEW YORK — A dreadful bullpen is making it awfully difficult for the New York Mets to avoid another September meltdown.

It seems manager Jerry Manuel has tried nearly every reliever in multiple roles. So there’s not much left for him to do besides hand someone the ball and cross his fingers.

Fill-in closer Luis Ayala gave up a go-ahead homer to pinch-hitter Greg Norton, and the Atlanta Braves rallied for five runs in the ninth inning Sunday and a 7-4 victory that trimmed New York’s tenuous NL East lead to 11/2 games.

“These are tough losses, especially this time of the year,” Manuel said. “We’ve been dealt many tough blows. We’ve got to see if we can make it back.”

Wasting two homers by David Wright and a strong start from Oliver Perez, the Mets lost for the ninth time in 30 games. Their lead could be cut to one game — two in the loss column — if second-place Philadelphia beats Milwaukee in the second game of a day-night doubleheader Sunday. The Phillies won the opener 7-3.

The Mets squandered a seven-game cushion with 17 to play last year, letting Philadelphia charge past them for the division title in one of the worst collapses in baseball history.

Desperately trying to erase those painful memories, New York had 17 games remaining coming into this series and dropped two of three to the fourth-place Braves (67-83).

“Coming down the stretch at this point, every loss will probably be a reminder of what happened last year,” Manuel said. “What we have to do as a team is get through it. We’ve got to finish.”

That’s been a problem all season.

The Mets have 27 blown saves — they began the day tied for third-most in the majors. This was their 11th blown save in the ninth inning. New York entered Sunday tied for third-most in that category as well, according to the Elias Sports Bureau.

“We need to pick each other up. We all know they’re trying to do their best,” Carlos Beltran said. “Right now, things aren’t working for them, but that doesn’t mean they’re not going to pitch better.”

Missing injured closer Billy Wagner for the rest of the year, the bullpen failed to hold an eighth-inning lead for Johan Santana in the opener of Saturday’s doubleheader and flopped again Sunday.

Despite the deflating loss, New York had some fun after the game with a familiar hazing ritual. Young players were dressed up as Olympic swimmers — fake medals, goggles, skintight swimsuits — as the team left town for its final road trip of the season.

“The next Michael Phelps,” a smiling Pedro Martinez said, pointing at 6-foot-7 Mike Pelfrey. “Don’t rip it. You’re still going to have to wear it.”

Ayala (2-9) began the ninth with a 4-2 lead but allowed consecutive singles to Casey Kotchman and pinch-hitter Kelly Johnson. Norton then drove a full-count delivery into the Mets’ right-field bullpen — appropriately — for a 5-4 Atlanta edge.

It was Norton’s third pinch-hit homer this season.

“I tried to throw my sinker down and away. The ball stayed in the middle,” Ayala said.

After he was lifted, the Braves tacked on two more. Gregor Blanco hit an RBI double off Pedro Feliciano, and Corky Miller’s sacrifice fly against Brian Stokes made it 7-4.

Jorge Julio (2-0) worked a scoreless eighth for the win.

The Mets tried to make a comeback of their own in the bottom of the ninth, putting their first two batters on. But Mike Gonzalez retired the next three for his 11th save in 12 chances.

“Our bullpen the entire series held for us. Both wins were because of the bullpen,” Braves manager Bobby Cox said. “We’re going to help the Mets as much as we can when we play the Phillies six times, so it’s our job to be up for every game and go at it as hard as we can.”

Atlanta slugger Chipper Jones had three hits, including an RBI double, in his final game at Shea Stadium, where he’s had so much success that he named one of his sons Shea.

The All-Star third baseman, who missed Saturday’s doubleheader with a stiff back, finished with a .313 batting average, 19 homers and 55 RBIs in 88 games at the ballpark.

“It was fitting, with all the close games the two teams have played over the years,” Jones said. “We’re a prideful bunch over here. We’ve been sitting where they are sitting now many times. ... We’re not going to roll over. If they’re going to beat us, they’re going to earn it.”