David Phelps was healthy. He just wasn't any good.

Making his first start since taking a line drive off his forearm, Phelps was rocked for five quick runs Wednesday night and got only one out for the New York Yankees in a 9-4 loss to the Mets.

"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."

Challenged by fed-up manager Terry Collins, slumping infielders Ike Davis and Ruben Tejada sparked a big first inning that kept the fourth-place Mets sailing along in this surprising Subway Series. 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 finale Thursday night at Yankee Stadium.

"I don't know if we really need to press. You look at the two games at Citi Field and we were right there," Phelps said. "The Mets are playing good baseball and you just tip your cap to them. They've beaten us three in a row and we'll come out tomorrow and try to spoil their fun."

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

"I think we know what we've got. I think we know what we're capable of doing. We just haven't been swinging the bats well," center fielder Brett Gardner said. "The Mets have really had our number."

Tejada hit a leadoff single in the first, Davis drove in two runs and the Mets won with Jeremy Hefner on the mound for the first time all season.

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.

"Those guys are a good team over there, they just haven't hit their stride," Yankees first baseman Lyle Overbay said. "But it seems like they've done that right now, so we've got to find a way to put a stop to it."

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.

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 — to give the Mets a 1-0 lead 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 was it for Phelps (3-3), who had won two consecutive starts. He went 7 2-3 innings last Friday at Tampa Bay before leaving when he was hit on his pitching arm by a line drive. The right-hander had trouble with his command Wednesday, but said his health was not an issue.

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

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.

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.

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. ... Girardi put slumping LF Vernon Wells on the bench and stacked his lineup with seven left-handed hitters against Hefner, who was holding righties to a .171 batting average. Lefties were hitting .338 against him. ... RHP Ivan Nova pitched the final five innings for the Yankees, allowing one run and five hits while striking out six. ... Tejada limped off the field in the ninth with a sore quadriceps and will be examined Thursday morning, Collins said.