Jamie Moyer shut down the slumping Mets on two singles that didn’t leave the infield, Greg Dobbs hit a three-run homer off Pedro Martinez, and the Philadelphia Phillies trimmed their NL East deficit to one game with a 6-2 victory in the opener of a day-night doubleheader yesterday.

Facing the first-place Mets for the sixth time this season, the 45-year-old Moyer allowed only a surprise bunt single by Robinson Cancel and an infield hit by Damion Easley over seven shutout innings.

New York was scoreless for 16 innings in the series before breaking through for two runs in the eighth against Scott Eyre, but it came too late.

Looking to leave town tied for first place, the Phillies send Cole Hamels to the mound in the nightcap. Johan Santana gets the ball for the Mets in a pressure-packed matchup of left-handed aces.

Philadelphia swept a three-game series at Shea Stadium last September, beginning its big comeback to overtake the collapsing Mets and win the division title.

The onus is on Santana, acquired from Minnesota last offseason and signed to a $137.5 million, six-year contract, to prevent another costly sweep against the Phillies.

After Brett Myers pitched Philadelphia to a 3-0 victory Friday night, Moyer (13-7) also was on top of his game when his team needed it.

Using his typical array of soft stuff and dashing out to the mound for warmup pitches even before the Mets lumbered off the field, he walked three and outpitched an ineffective Martinez (5-4) in the makeup of Saturday’s rainout.

Philadelphia improved to 7-10 against the Mets this season. The Phillies won the final eight matchups last year.

Moyer’s 243rd win tied him with Hall of Famer Juan Marichal for 50th on the career list. The lefty is 6-1 with a 2.97 ERA in his past 12 starts. Now 2-1 against the Mets this year, he has pitched at least six innings in 19 of his 20 career starts versus New York.

Martinez lasted only four innings, giving up six runs and seven hits. He felt stiffness during his previous start, a win at Florida, and returned to New York to work out while the Mets completed a 6-2 road trip with a three-game sweep in Milwaukee. The 36-year-old right-hander entered 2-0 in five starts since losing 4-2 to San Diego on August 6.

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MARINERS 5, YANKEES 2 Jose Lopez hit two homers, Ryan Feierabend went from idle to impressive and the Seattle Mariners sent the Yankees tumbling into fourth place with a 5-2 victory yesterday.

Lopez’s liner just over the wall in left field gave Seattle a 3-2 lead in the fourth off Mike Mussina (17-8), who allowed four runs and seven hits and made a key error — his first in three years — in six innings.

Lopez added his 14th home run of the season in the eighth off Jose Veras. It was Lopez’s first multi-homer game.

Miguel Batista pitched a perfect eighth before the Yankees had two on and one out in the ninth against J.J. Putz. But Putz struck out a flailing Robinson Cano and then pinch-hitter Wilson Betemit for his 12th save in 20 chances.

New York lost two of three games to the team with the worst record in the AL.

The Yankees, who have made the postseason for 13 consecutive years, trail the Red Sox by 8 1/2 games in the AL wild-card standings with 19 games remaining. Perhaps more tellingly, they fell into fourth place in the AL East behind Toronto, which beat Tampa Bay 1-0.

They were done in this time by Feierabend, a 23-year-old who showed up to work yesterday thinking he wasn’t going to pitch until Wednesday. Then Carlos Silva told the Mariners he couldn’t start because of sharp pains in his upper back.

Feierabend (1-2) allowed just five hits — including solo home runs by Derek Jeter and Xavier Nady early — in seven innings for his second win in 11 career decisions.

In the third, Jeter singled under the glove of diving shortstop Yuniesky Betancourt to tie Babe Ruth for second on the Yankees’ all-time hit list. It was Jeter’s 2,518th hit.

Lou Gehrig has the New York record with 2,721 hits.

Alex Rodriguez helped squander a rally with New York trailing 3-2 in the fifth. After Rodriguez walked with two outs and Jeter already at second, lefty Feierabend caught Rodriguez far off first base. In the ensuing rundown, first baseman then Bryan LaHair threw to third base and Beltre ran down Jeter to end the inning.