ATLANTA — The Mets were an angry bunch Thursday night at SunTrust Park.

The 6-4 loss Wednesday night frustrated them to no end and they were determined to leave little to chance.

Or questionable managerial decisions.

Competitive fire was on display from the start as Pete Alonso blasted a 451-foot three-run home run in the first inning, tying Cody Bellinger for the most homers ever hit in the NL by a rookie with 39, the first of Alonso’s five hits.

Amed Rosario continued his Jeff McNeil-leadoff impersonation with five hits of his own, a career high, and Todd Frazier lifted his 16th home run of the season in the Mets’ 10-8, 23-hit victory over the Braves to salvage the final game of the series.

Turns out they would need nearly every hit and run as the Braves (six home runs on the night) scored five times in the last two innings.

With the 43-78 Royals on tap in Kansas City, the Mets are looking at a much brighter weekend before they have to face a quality opponent again in the Indians on Tuesday at Citi Field. The Mets are two games back in the wild-card race.

After a couple tough losses and the loss of McNeil (hamstring injury), this was desperately needed.

“We needed to win today, for sure,’’ Alonso said. “Hopefully we can keep this momentum going. It was a really good team win today. It’s a big series in Kansas City for us. Every game matters at this point in the year. We’re right there in the hunt.’’

Rosario echoed those thoughts, saying through a translator, “It feels important for us because after losing the first two games of the series it helps us regain our confidence, not only for me but for the rest of the team.’’

Mickey Callaway’s fateful decision to yank Steven Matz out of Wednesday night’s game with a 2-1 lead, after the lefty had retired 14 straight, cost the Mets a critical game. The Braves scored five times in the seventh against Seth Lugo, who had the worst performance as a reliever of his career as Atlanta came away with the win.

The Mets took care of business early Thursday night against a once-again dreadful Julio Teheran. The offensive fire was highlighted by Alonso’s blast into the pond in deep center field over the evergreens. Alonso produced a six-RBI game, only the third Mets rookie to do so.

That helped a wild Marcus Stroman, as the right-hander lasted 5 ¹/₃ innings to get his first Mets win. The Mets have Noah Syndergaard, Jacob deGrom and Zack Wheeler lined up for the Royals as they get a little taste of what the Yankees have taken advantage of all season — the opportunity to pounce on pathetic AL teams to create a victory cushion.

Certainly, Callaway did not help his Mets managerial future with such a critical decision blowing up in his face Wednesday. General manager Brodie Van Wagenen is looking at a lot of factors and, remember, he inherited Callaway.

Interestingly, Callaway dug in deeper on his thought process.

Asked if any of those decisions in the seventh inning Wednesday night were scripted in advance, Callaway said, “No. Obviously we hit Matzy. I thought he was throwing the ball well. I thought that if we were still down or tied that he pitched well enough to go out there. Once I thought we were going to take the lead in real time once he got on base and had to run the bases, we were going to get Lugo in there but nothing was pre-scripted about it.’’

That means this was solely Callaway’s move. He felt he could lock it down with Lugo, who had been terrific in retiring 26 straight batters from July 21 to Aug. 10.

So Callaway would have stayed with Matz, who had only 79 pitches, only if the Mets were tied or trailing. Once they got the lead Matz was done and Callaway was betting that the Mets bullpen could come up with three clean innings against the first-place Braves.

It didn’t work.

The answer to the problem is simple.

Get a bigger lead and make the decisions easier, and that is what the Mets did from the start Thursday night.