ATLANTA — Travis d’Arnaud, a former Met, hit a walk-off homer in the ninth inning and the Atlanta Braves kept up their postseason push with a 2-1 win over the playoff-bound Kansas City Royals on Saturday night.

Reynaldo López came off the injured list to throw six strong innings for the Braves, who moved one game ahead of the Mets and a half-game in front of Arizona for the final two wild-card spots in the National League.

The Mets lost 6-0 at Milwaukee and the Diamondbacks were hosting San Diego.

D’Arnaud ended it with one swing in the ninth, launching a 2-0 pitch from Sam Long (3-3) over the center-field wall for his 15th homer this season.

Raisel Iglesias (6-2) earned the win.

López pitched for the first time since Sept. 10, when he lasted only one inning at Washington before coming out with shoulder discomfort.

An MRI exam showed no structural damage, but the Braves placed him on the 15-day disabled list in the heat of playoff race to make sure things didn’t get worse.

López looked as good as ever in his return, allowing only two singles while striking out nine. After fanning Adam Frazier with the last of his 73 pitches, he pounded his glove in satisfaction walking off the mound, having lowered his ERA in a dazzling season to an even 2.00.

Kansas City went ahead in the third after starting the frame with its only two hits off Lopez — back-to-back singles by Freddy Fermin and Garrett Hampson. Fermin came home from third when Dairon Blanco hit into a double play.

The Braves tied it up in the fourth with an unearned run.

With two outs, Jorge Soler hit one off the yellow line at the top of the wall in right-center for a double. D’Arnaud followed with a dribbler that was fielded by pitcher Michael Lorenzon, who had plenty of time to get the slow-running catcher but threw it in the Braves dugout.

Soler came home on the error.

The Royals went with a makeshift lineup one day after clinching their first postseason appearance since 2015.

Bobby Witt Jr. was among six starters from Friday’s 3-0 loss who got the night off, while three others were slotted into different positions.

For Witt, it was the first game he’s missed all season after making 160 consecutive starts — 159 at shortstop and one game as the designated hitter.

Sitting out had an added benefit for the Royals star, who likely locked up the AL batting title with a .332 average and just one game left in the regular season.

Sixteen-game winner Seth Lugo pitched two scoreless innings for Kansas City, limited to 36 pitches in what was essentially a tune-up for the Wild Card Series that begins Tuesday.