Atlanta Braves pitcher Alex Wood pitches during the first inning of a baseball game against the New York Mets at Citi Field Wednesday, Aug. 21, 2013 in New York.

NEW YORK - Chris Johnson hit a three-run homer in the 10th inning and Atlanta beat the New York Mets 4-1 on Wednesday after Braves outfielder Jason Heyward was hit in the right jaw by a pitch.

Heyward went down in a heap during a scary scene at Citi Field in the sixth. He was examined by Mets doctors and taken to a hospital for X-rays.

Atlanta, with the best record in baseball and a huge lead in the NL East, got an RBI single from Freddie Freeman and another impressive start by rookie Alex Wood in splitting the two-game series for its 20th victory in 24 games. The Braves also benefited from a disputed call in the 10th.

Andrelton Simmons singled off Scott Atchison (3-2) with two outs and Freeman hit a two-strike grounder back toward the box that ticked off the bottom of Scott Rice's glove and rolled behind him. The reliever retrieved the ball and fired to first, where Freeman was called safe.

Mets manager Terry Collins came out to argue with umpire Jerry Layne before Johnson launched a drive to left field on Greg Burke's first big league pitch since he was recalled from the minors on Sunday.

Johnson, who began the day second in the NL in batting, struck out his previous three times up.

Seconds after Johnson crossed the plate, Layne ejected New York second baseman Daniel Murphy. Collins came out for a more vehement argument this time, tossed his hat to the ground and also was thrown out by Layne.

Collins walked back to the dugout without retrieving his cap, leaving it there in the dirt by Layne's feet.

The crowd of 22,935 gave Layne a derisive cheer when he called a Mets runner safe in the bottom of the 10th.

Luis Avilan (5-0) pitched out of a bases-loaded jam in the ninth and Craig Kimbrel reached 40 saves for the third straight season. He has converted 30 chances in a row, extending his club record.

Simmons and Freeman each had three hits.

Josh Satin homered for the Mets, and Jonathon 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.

Wood allowed one run over six innings in his seventh major league start - three against the Mets. The 22-year-old lefty, drafted in the second round last year out of Georgia, moved into the rotation with a shaky outing July 25 at Citi Field but has followed that with five strong starts in a row.

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.

An inning later, the Mets announced that Heyward was examined by their doctors before he was taken to the hospital.

On a tear at the plate since moving into the leadoff spot last month, Heyward began the day batting .254 with 13 homers and 37 RBIs.

Niese struck out Schafer with the bases loaded to end the seventh, not long after Paul Janish tried to drive in a runner from third with a two-strike bunt. The ball rolled foul for strike three.

In his third outing since missing almost two months with a partially torn rotator cuff, Niese gave up five hits in seven innings.

NOTES: Braves OF Justin Upton missed the series with a strain in his upper back. He was replaced Wednesday by LF Joey Terdoslavich. ... Upton's brother, B.J., started in CF on his 29th birthday. He went 0 for 4 with two strikeouts and is hitless in his last 24 at-bats. ... Johnson batted cleanup for the second time this season. ... Satin has reached base safely in all 29 of his starts this season, the fourth-longest streak in the NL. ... New York C John Buck made 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.