ATLANTA — Philadelphia Phillies outfielder Nick Castellanos called the postseason a “fresh start” for him after helping his team to a 7-6 victory over the Atlanta Braves in Game 1 of the National League Division Series on Tuesday.

Castellanos, 30, had three hits and three runs driven in, plus a ninth-inning, diving catch in right field to help seal the win for the visiting team.

“It’s kind of just a fresh start, a clean slate, so to speak,” Castellanos said after the game. “And obviously these games are really intense. For me, that helps me lock in and kind of slow things down. It’s just a lot of fun.

“Baseball is really, really fun.”

That may not have been the case for the veteran for much of the regular season, as his numbers were well below his career averages. He compiled an OPS-plus of just 95, the lowest of his 10-year career.

“The one thing that all of us in this room share in common is we want to contribute to the club as much as we can every night,” teammate Rhys Hoskins said. “When you’re not doing that it wears on you.

“The thing I’ve been impressed with is he’s the same guy. He comes in, gets his work in, and off he goes in the game. It’s awesome to see him have success today.”

Castellanos signed a five-year, $100 million deal with Philadelphia in the offseason, struggled, then got hurt late in the year. He returned for the final nine games of the regular season while producing an OPS of just .536.

Going 0-for-7 in the wild-card round didn’t help matters, but that all changed on Tuesday. Castellanos had an RBI single in the first inning, a double in the third, then a two-run single in the fourth, becoming the first Phillies player with a 3-hit, 3-RBI game in the postseason since Jayson Werth in the 2009 NLCS.

“Today (my swing) felt great, and that’s the only thing really that I’m focused on and then getting ready to go and make sure it feels great again tomorrow,” Castellanos said.

Not known for his defense, he capped off his stellar day with a diving catch at the most important moment in the game.

The Braves had just narrowed their deficit to one run on a Matt Olson three-run homer in the ninth before Castellanos sprinted in on a line drive off the bat of William Contreras. He laid out for it, snaring the ball just before it hit the grass.

He was asked if he was happy or just relieved as he lay on the ground afterward.

“All the above,” he answered with a smile. “Just looking (up), like, thank God I caught that ball. They obviously had a big point in the game right there with putting them within one. So to be able to catch that and have two outs and nobody on was huge.”

Hoskins added: “I was screaming at him, ‘C’mon, c’mon, stay up.’ You could feel momentum right there. They had it after the homer. To get the next guy out is huge.”

Castellanos’ first two hits came off Braves starter Max Fried, who lasted only 3⅓ innings while giving up six runs, four of them earned — though he made the error allowing the other two to score.

Fried’s velocity was down a tick and his stuff wasn’t great. It led to questions about his health, as Fried was recovering from an illness over the final week of the regular season. He downplayed it.

“It stayed with me for longer than we were expecting,” Fried told reporters. “It’s one of those things you just have to battle.

“I’m not going to make any excuses. I took the ball today and put us in a big hole, right off the bat.”

Braves manager Brian Snitker noticed something was off with Fried, who left a game early against the New York Mets in late September.

“I asked him after the fourth, when he came off,” Snitker said. “He went down and he was mad and everything. I just wanted to make sure he was OK physically. And he just kind of wasn’t firing today.

“He had the flu, the last game he pitched against the Mets. But he’s been doing everything, throwing his sides. Did all the drills, did everything. Just didn’t happen for him today.”

And so the Phillies took advantage, led by one of their quiet stars who was coming off a quiet regular season. Perhaps the tide is turning for their right-fielder after helping his team to a mid-October win.

“I can’t explain (the postseason),” Castellanos said. “It’s one of those things that the air is different, the atmosphere is different. And those are all things that I really enjoy.”