Following an intentional walk to Daniel Murphy, Mayberry sent a ground ball deep enough into the shortstop hole that Jhonny Peralta could not throw out Campbell racing home.
The Mets initially seemed headed to a breezy victory behind Harvey, who pushed his pitch count to 105 over eight shutout innings. But the Mets scored just once off starter John Lackey and closer Jeurys Familia blew his first save in 14 chances, giving up Jason Heyward's game-tying sacrifice fly in the ninth.
Both Harvey and Lackey were on point from the start, trading zeros for much of the early evening.