Josh Satin homered for the Mets, and Niese struck out a season-high nine for the second consecutive start. Rookie center fielder Juan Lagares turned in his latest defensive gem with an outstanding throw to cut down Simmons trying to stretch a one-out single in the fourth, Atlanta's first hit off Niese.
Heyward was struck by a 90 mph fastball from Niese in the sixth. The impact made a loud noise, and the crowd groaned as Heyward crumpled to the ground.
He stayed down on his back for about three minutes before getting helped to his feet. Heyward walked slowly off the field under his own power, escorted by a trainer, and was replaced by Jordan Schafer.
Visibly concerned, Niese tapped himself with his glove as Heyward walked off, and Heyward appeared to acknowledge him.
Perhaps a bit shaken, Niese then gave up singles to Simmons and Freeman in a three-pitch span as Atlanta tied it at 1.
NOTES: New York went 0 for 9 with runners in scoring position. ... Mets C John Buck was 0 for 3 with an intentional walk in his first start since returning from paternity leave. ... Mets RHP Jeremy Hefner, expected to have Tommy John surgery soon, said he is scheduled to see Dr. James Andrews on Monday for another opinion on his injured elbow. "Just to make sure I cover all my bases and do what's best for my career," Hefner said. ... New York's weekend series against AL Central-leading Detroit includes a rematch of All-Star game starters at Citi Field: Max Scherzer (18-1, 2.82 ERA) faces Mets ace Matt Harvey (9-4, 2.25) in a nationally televised game Saturday. ... Satin has reached base safely in all 29 of his starts this season, the fourth-longest streak in the NL. ... Wood went six innings in his seventh major league start — three against the Mets.