As the Mets and Cubs found their footing all the way to a 2015 NLCS showdown, the youthful teams inspired thoughts of a budding rivalry.

The new blood is now bad blood as a co-owner of the Cubs introduced himself to New Yorkers on Saturday with a few shots at the fans who inhabit Citi Field.

“I don’t know if you know this, but Mets fans are really, really obnoxious,” Todd Ricketts told a Cubs Convention audience at the Sheraton Grand Chicago.

The Cubs board member said he and his wife had enjoyed his team’s trip across the country for the playoffs, saying they had relished Pittsburgh, where Chicago won the wild-card game, and appreciated the “hospitable” fans in St. Louis.

“And then we went to New York,” Ricketts said, letting the moment breathe for fans to laugh before his “obnoxious” prods.

New Yorkers left an impression on Ricketts and his wife, even after the Mets rolled past Chicago in a sweep. But the family’s focus went from the stands to the mound.

“My wife and I are sitting in our living room. It’s 10:30 at night,” Ricketts said, according to CSN Chicago, reliving the Mets’ fateful Game 5 loss to the Royals. “We’re in our pajamas. I don’t know if you guys remember — Matt Harvey refused to come out of the game.”

Mets fans remember. The ace then unraveled in the ninth before being lifted for Jeurys Familia, who allowed the game-tying run by Eric Hosmer to extend the game three innings, after which the Royals would emerge as World Series champions.

“When Hosmer’s left hand went across home plate,” Ricketts said, “my wife jumped up, pointed at the TV and she said: ‘Screw you, Matt Harvey! Screw you, Mets fans!’ ”

The Mets will play host to Chicago from June 30 to July 3, for those awaiting the date.