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Once the Subway Series rolled around, the New York Mets got on the right track.

Challenged by fed-up manager Terry Collins, slumping infielders Ike Davis and Ruben Tejada sparked a five-run first inning that kept the Mets sailing along in this surprising set with a 9-4 victory over the Yankees on Wednesday night.

Tejada hit a leadoff single, Davis drove in two runs and the fourth-place Mets won with Jeremy Hefner on the mound for the first time all season. They've taken three in a row from their crosstown rivals for their first four-game winning streak of the year and will go for a Big Apple whitewash in the series finale Thursday night at Yankee Stadium.

"Some great at-bats in the first inning," Collins said. "I just think there's a different attitude in the clubhouse."

Yankees starter David Phelps (3-3) got only one out — but said his health was not an issue. The right-hander, who had trouble with his command, left his previous outing after he was hit on the right forearm by a line drive.

"It's nothing at all. Arm felt great today. Just wasn't making pitches," he said. "The ball was just up and in the middle of the plate a lot."

The suddenly-slumping Yankees dropped their fourth in a row. Despite a rash of injuries to star players, they began the night a game behind first-place Boston in the AL East.

"The Mets have really had our number," center fielder Brett Gardner said.

By the late innings Mets fans were chanting "You can't beat us!" in a mostly empty Yankee Stadium, where the outlines of a soccer field were still visible on the grass following Saturday night's exhibition match between English Premier League teams Chelsea and Manchester City.

After rallying two nights in a row back home at Citi Field for a pair of tense, 2-1 wins, the Mets made this one a virtual laugher right off the bat by building an 8-0 lead. But they still had their confounding moments — Tejada had another mental lapse at shortstop that helped the Yankees score twice in the sixth.

That brought Collins, looking more than a little irritated, to the top step of the dugout. He stared out in Tejada's direction and then jotted something down on a piece of paper.

"I have to concentrate on my job," Tejada said. "I have to get better every day and go play hard every day."

With two outs in the bottom of the ninth, Tejada limped off the field with a sore quadriceps. He was hurt chasing a foul fly down the left-field line and will be examined Thursday morning, Collins said.

"I don't think it's too bad," Tejada said.

Without divulging details, Collins acknowledged before the game that he met Tuesday night with Davis and Tejada and told them in no uncertain terms it was time to snap out of it and start producing — right now.

WFAN radio reported both players were informed they were on the edge of being demoted to the minors.

In the first inning, they responded.

"Obviously, I don't like playing bad," Davis said. "The fire's been lit for a while. I've been upset all year."

Tejada snapped an 0-for-12 skid and scored from first on Daniel Murphy's double to deep right-center — finally a drive off his bat that Gardner couldn't chase down — and the Mets were ahead 1-0 after three pitches.

Gardner robbed Murphy of extra bases with two spectacular catches the previous two nights.

John Buck beat the defensive shift with an RBI single to right and the Mets scored again when third baseman Jayson Nix bobbled Marlon Byrd's RBI grounder for an error.

Davis was batting .152 when he stepped to the plate with the bases loaded. He worked an 0-2 count full and lashed a sharp single past shortstop to make it 5-0.

"That's a five-star at-bat if you ask me. With guys in scoring position, that was huge," Buck said. "You can just see the quality of his at-bats literally the last week. They're completely different."

That was it for Phelps. The last Yankees starter who failed to get more than one out in a game was Darrell Rasner on May 19, 2007, also against the Mets, according to STATS.

"He just didn't have it," Yankees manager Joe Girardi said. "He felt great yesterday, he just had a stinker."

Davis later hit a line-drive single to center, another encouraging sign. He began the night 4 for 53 (.075) with 24 strikeouts in his past 16 games — and hitless since a tiebreaking single in the eighth inning to beat Atlanta on Sunday night.

Hefner (1-5) gave up three runs and nine hits, including Brennan Boesch's solo homer, over six innings in his second start since his Oklahoma hometown was ravaged by a tornado last week. The Mets lost all nine of his previous starts this season — and even when he made his lone relief appearance.

"It's great to win, but more importantly keep our team winning streak going,'" Hefner said.

Byrd homered and Lucas Duda, who had the game-winning hit off Mariano Rivera on Tuesday night, added a two-run double for the Mets, who scored their most runs since a 16-5 win April 12 in Minnesota.

NOTES: Mets RHP Dillon Gee (2-6, 6.34 ERA) faces LHP Vidal Nuno (1-1, 1.93) in the Subway Series finale Thursday night. ... It was Hefner's first start at Yankee Stadium.