The Mets were one out away from turning a bad day, into a feel good win - until everything came crashing down.
After Edwin Diaz blew a five-out save in the first half finale to the Pirates last weekend, he picked up right where he left off on Saturday night in the ninth inning.
The Mets jumped out to a 6-0 lead, but the Pirates eventually exploded with five runs of their own off of Seth Lugo in the bottom of the eighth.
But Brandon Nimmo gave the Mets a much-needed insurance run in the top of the ninth with a solo home run to extend his team's lead to 7-5.
However, the Pirates loaded the bases against Diaz in the bottom half, and that's when Jacob Stallings stepped to the plate and cracked a walk-off grand slam to send everyone home.
All of a sudden, the Mets were handed their worst loss of the season, for the second time in six days.
"I couldn't believe it when it cleared the fence," said Diaz, who has now blown two saves in his last two chances, doubling his total on the season. "I thought it was a fly ball."
Diaz and Lugo uncharacteristically combined to allow nine runs to the Pirates' offense in the final two innings.
"Our clubhouse, we're mentally stronger than that," said Lugo after the game. "It's not gonna get us down.... one loss doesn't define the team. We're a good ball club and we're gonna show it tomorrow."
Unfortunately, J.D. Davis' big evening wound up being overshadowed, as was rookie pitcher Tylor Megill's stellar performance.
Davis hit two, two-run homers, while Travis Blankenhorn and Jeff McNeil each drove in a run to give the Amazins' a six-run lead.
And Megill impressed once again with a career-high six shutout innings in his fifth major league start. Megill now has a 2.63 ERA on the season, but has yet to notch his first big-league win.
However, the bullpen couldn't hold things down, as the Mets blew it in the final two innings behind meltdown performances from their top two relievers.
The Mets are now 47-42 and their lead in the NL East has shrank to just 2.5 games. They will look to avoid the sweep in Pittsburgh on Sunday with All-Star pitcher Taijuan Walker on the mound.