The final pitch ended up as a looping RBI single to rightfield by Lucas Duda to score David Wright with the winning run. The Mets rallied for two in the ninth to beat the Yankees for the second straight game, 2-1.
It was Rivera's first blown save in 19 chances this season and his third career against the Mets. It also was the first time in his career that he blew a save without getting an out.
"Hopefully, it's the last one,'' Rivera said. "God knows. What can I say? It was a great game until I got into the game.''
Said Wright: "I think we surprised ourselves. Because when you get Mo coming in, it's usually game over.''
The inning began with Daniel Murphy's ground-rule double that he sliced down the leftfield line. Wright followed with a tying single to center and moved to second when Chris Stewart bobbled the throw home. The error was charged to centerfielder Brett Gardner, but Rivera blamed himself for not backing the play up.
"I should be back there,'' Rivera said. "There's no excuses.''
"There's no words to explain it right now,'' said Mets manager Terry Collins, who was ejected in the sixth inning for arguing a reversed (but ultimately correct) pickoff call against Ruben Tejada at second base. "That's the way the game is . . . once in a while, things happen.''
The Yankees have lost three in a row. The new-format series moves to the Bronx Wednesday night for the first of two at Yankee Stadium.
"This series, to us, is huge,'' Collins said. "This is a big, big series. This is a team that's struggling against a team that's playing great. We're frustrated, they're not. This means a lot to us.''
Starters Matt Harvey and Hiroki Kuroda were magnificent. Neither walked a batter.
Harvey allowed one run in eight innings -- and it was a tainted but technically earned run in the sixth. Gardner led off with a single to right that was booted by Marlon Byrd for an error as Gardner took second. He moved to third on a groundout and scored on Lyle Overbay's two-out single to center.
Harvey kicked the dirt in front of the mound in disgust after Overbay's hit. After the inning, he slammed his glove down on the dugout bench.
Harvey allowed six hits and struck out 10. Kuroda, who threw seven shutout innings, gave up four hits and struck out seven.
It was to be the retiring Rivera's last scheduled appearance in the Mets' ballpark -- unless the teams meet in this season's World Series.
Even Mets chief operating officer Jeff Wilpon doesn't think there's a chance that will happen.
Wilpon, in a ceremony in which the Mets and the FDNY presented Rivera with a pair of fireman-themed gifts, told the Yankees closer: "I wish we could see you in the World Series, but I'm not sure that's going to happen this year.''
Rivera, smiling, said, "You never know.''
Rivera's first pitch, and the game, were delayed 1 hour, 31 minutes at the start by rain. At 8:32, Rivera emerged from the third-base dugout and was greeted with a partial standing ovation from the crowd of 31,877. Franco came out from the first-base dugout, bowed to Rivera in an "I'm not worthy'' motion, and caught the pitch.
Rivera might have one more opportunity to pitch at Citi Field: in the July 16 All-Star Game.