WHAT IT MEANS: The euphoria generated by Johan Santana’s no-hitter nine days ago officially is extinguished.

A pair of infield miscues opened the door for a Yankees comeback as the Mets failed to protect a three-run lead over the final three innings. The Amazin’s ultimately were swept in the Subway Series with a 5-4 loss Sunday. Russell Martin delivered the walk-off win in the bottom of the ninth with a leadoff homer against Jon Rauch.

The Mets (32-29) were swept in the Bronx for only the second time since the inception of the Subway Series in 1997.

Having squandered a three-run lead, the Mets opened the ninth with consecutive doubles by Lucas Duda and Ike Davis against Rafael Soriano to pull even at 4 -- with Duda’s shot misread by center fielder Curtis Granderson. Davis, who produced his first ninth-inning hit in nine at-bats this season, then was erased at third base on a grounder to shortstop.

Where did things unravel?

With the Mets leading 3-2, Omar Quintanilla had a grounder from Derek Jeter roll under his glove to begin the bottom of the eighth, and the Yankee captain hustled to second base. Jeter ultimately scored the tying run on Mark Teixeira’s single up the middle against Bobby Parnell. Alex Rodriguez followed by driving in the go-ahead run with a bloop single to shallow right field.

The Mets held a 3-0 lead with two out into the seventh behind Jon Niese, when David Wright’s two-out throwing error, which Vinny Rottino could not handle at first base, allowed Andruw Jones to reach. Martin followed with a two-run homer to the short porch in right field at Yankee Stadium for a pair of unearned runs that pulled the Yankees within a run.

Now at the midpoint of a stretch of eight straight series against teams with winning records, the Mets still have series with the Rays, Reds, Orioles and Yankees remaining in that stretch. So far against the Phillies, Cardinals, Nationals and Yankees, the Mets are 5-8.

Three of the wins came in the four-game series against the Cardinals that included Santana’s no-hitter.

Mark Simon of ESPN Stats & Information notes that six times this season Parnell has induced a groundball that has resulted in the batter reaching via error. (Jeter’s technically was scored a single, with the error allowing him to reach second base.) Thirty-five of the 84 balls his in the ballpark against Parnell have been hits or errors -- an amazingly high total.

THEY WERE HEROES: Using a makeshift lineup, the Mets received contributions from Rottino and Jordany Valdespin, who combined to drive in three runs in the second inning.

That rally actually stalled when Jason Bay and Wright consecutively struck out with the bases loaded. Bay is 0-for-11 since returning from the DL.

Scott Hairston continued to torment left-handed pitching as well as the Mets built the early lead. Hairston doubled and scored in the second inning on Rottino’s single. Hairston then singled in his next at-bat, although Andy Pettitte’s pickoff move froze him and led to a caught stealing (as was the case with Wright two innings later).

Rottino was starting at first base over Davis against the southpaw. Davis entered as a defensive replacement for the bottom of the eighth with the Mets trying to protect a one-run lead -- one inning after Rottino could not handle Wright’s throw at first base.

Hairston went 2-for-3 against Pettitte, upping his average against left-handed pitching this season to .364 (24-for-66). He also has started to see more action against righties, starting not only Thursday’s series finale in D.C. once Bay was scratched but also Friday’s series opener in the Bronx as well against Hiroki Kuroda.

WHAT’S NEXT: The Mets plan to fly to Tampa after the game and spend an off-day with their families in Florida. They return to action Tuesday against the Rays, with Chris Young making his second major league start since returning from shoulder surgery. Young (0-0, 3.60 ERA) opposes right-hander Alex Cobb (2-2, 4.12).