ATLANTA — The Mets’ Achilles heel is their defense and their inability to stop the stolen base.

The Braves’ athleticism will test the Mets over this three-game series that began Tuesday night at SunTrust Park.

Against the three first-place teams and all the wild-card contenders not named the Nationals, the Mets entered Tuesday with a 15-32 record. But that was against those other Mets — not these Mets who have shown a togetherness that is off the charts during their comeback streak when they had won 15 of the last 17 games and have won six straight series.

Win this series against the Braves and the Mets will be in the hunt for the NL East crown, something they were talking to The Post about in Pittsburgh, where Mickey Callaway said, “We are ready to make a run at this thing.’’

To keep going in that direction, they need to play a more complete game, especially against the Braves. That is the challenge.

“It’s the athleticism,’’ Callaway said Tuesday night about what scares him most about the Braves. “They are going to take off on you.

“You have to control the running game. Their lineup is very good. They have one of the best hitters in all of baseball in Freddie Freeman and Ronald Acuña Jr., I mean both of those guys are some of the best and you surrounded by other good ones.

“So we have to execute pitches. We have to be diligent in controlling the running game, and we have to make every play. We have to do the small things right to score runs. It’s a tough challenge. They are a great team, but if we play the way we are capable of and the way we have been playing lately, we have a good chance.’’

The Mets went into the series with a 27-36 record on the road. The last time here, the Mets lost two of three, giving up 14 runs the final two games, and the next day pitching coach Dave Eiland was fired and replaced by Phil Regan. The Mets went on to lose eight of the next 10, but have turned it around since the All-Star break.

The Braves had won six of the past eight games against the Mets, averaging 6.9 runs per game. The Braves are playing 18 of the next 24 games at home, and that is the time to take off and lock down the NL East. The Braves held a six-game lead over the second-place Nats and an eight-game lead over the Mets.

Acuña owns 33 home runs and an NL-leading 28 stolen bases, leaving him two shy of the fifth 30/30 season in Braves franchise history.

The Mets entered the series having allowed 102 stolen bases this season, the most in the majors. The next closest team is the Dodgers, who have allowed 77. Ron Gant was the last Brave to have 30 stolen bases and 30 home runs, and that was back in 1991.

But the Mets have been leap-frogging teams and are a confident bunch.

“We just need to keep having different guys in the lineup carry the load,’’ Todd Frazier said. “It’s not just about one player. It’s about all of us.’’

Interestingly, the Mets have taken a pair of players on the injured list, Robinson Cano and Dom Smith (and his scooter), on the trip. The Dom Scooter, which sports the mock-up NY license plate LFGM 2019, has become a thing.

“We want Dom out there on his little scooter when we win a game, that’s always fun,’’ Callaway said. “Dom is up and down the bench the whole game cheering for his teammates.’’

Asked if the scooter has been nicknamed yet, Callaway smiled and said, “I guess it’s whatever it says on the front there. I think he has a New York license plate on there. He was driving it around the hotel today.’’

Callaway said the Mets are just focusing on one day at a time.

“We understand where everybody is at,’’ he said.

Translated that means the Mets certainly are aware another big run will put them in the running for the NL East.

They just need to keep the athletic Braves in check.