PHILADELPHIA -- Be ready, everybody. Kyle Schwarber is up.

He crushed a first-pitch fastball from D-backs starter Zac Gallen for a leadoff home run in the first inning of Monday night’s 5-3 victory over Arizona in Game 1 of the National League Championship Series. It was a 117.1 mph rocket that crashed into the video board hanging from the second deck in right field, whipping an already raucous crowd of 45, 396 into a frenzy. The blast was Schwarber’s MLB-record fourth career leadoff homer in the postseason, and it was a tone-setter, as the Phillies continued to cement Citizens Bank Park’s reputation as baseball’s best home-field advantage in the playoffs.

“It’s a fun thing when you’re walking up to the plate and next thing you know, 46,000 people are getting on their feet and ready to rock and roll,” Schwarber said. “You’re looking to set a tone. If it’s a home run, if it’s a walk, a single, whatever it is, to try to get on base for these guys behind me. It’s a really special thing.

“Those are the things I’m not going to forget, ever, whenever I’m done playing … walking up to the plate in these playoff games and hearing these crowds roar.”

Two batters after Schwarber did his damage, Bryce Harper belted a home run to right-center field to give the Phillies a 2-0 lead.

One inning later, Nick Castellanos hit an opposite-field home run to give the Phils a 3-0 lead.

Harper celebrated his 31st birthday on Monday with his third homer in three games. He held up three fingers on his left hand and one finger on his right hand as he crossed home plate. He blew out the makeshift birthday candles.

“Sometimes I just do stuff, and that just felt right,” Harper said. “I just thought about it as I was running around third base that I would do it.”

Castellanos has homered five times in his past three games, joining Reggie Jackson (1977 World Series) as the only two players with five homers in a three-game span in a single postseason.

“If we don’t win seven more games, it means very little to me,” Castellanos said.

Phillies ace Zack Wheeler allowed two runs on three hits in six innings, while the bullpen allowed one unearned run over three innings to save it. The Phils have trailed only two full innings in their first seven postseason games, the second fewest for any team in a single postseason, according to the Elias Sports Bureau. They have outhomered the opposition by 12 homers (16-4), which is the best home run differential in any seven-game span in any single postseason.

Schwarber’s homer kept everything rolling.

“When he does that, it puts the entire night in our favor,” Castellanos said. “All the momentum, the whole stadium, the atmosphere, everything tilts toward the Phillies. I haven’t played in a lot of postseason games, but I’m learning that momentum is very important.”

Phillies fans had barely touched their crab fries when Schwarber connected on Gallen’s first pitch. They weren’t alone.

“I barely got my Red Bull cracked,” reliever Matt Strahm said.

“Any time he’s up, you might think it’s going to be 1-0,” second baseman Bryson Stott said. “That’s why we called him, ‘1-0.’ Yeah, that was crazy. I wasn’t even standing up yet. I was still putting my stuff on. He hit it pretty fast. [Jake] Cave still had his coffee in his hand, that’s how you know it was early.”

“I was putting my contacts in the bathroom when it happened,” reliever Jeff Hoffman said. “I was on my way out and the ball was in the air. So I heard the roar and I was already on my way out.”

The funny thing is, Hoffman predicted it would happen. Phillies relievers play a game in the bullpen where whenever they think one of their teammates is going to homer, they toss their cap in front of them. If they guess correctly, they win a prize.

“As soon as Wheels made the last out, I threw my hat,” Hoffman said. “I knew that Gallen is a big first-pitch fastball guy, and we’ve got a guy that really loves hitting first-pitch fastballs. So it was like a perfect storm. Schwarber is your best odds in a lot of different scenarios. Even if it’s later in the game, I throw my hat for Schwarbs all the time, because he’s just lightning in a bottle.”

Schwarber’s homer had an exit velocity of 117.1 mph, making it the fourth-hardest-hit home run in the postseason since Statcast began tracking in 2015, and the second-hardest-hit ball for a hit by a Phillie in the Statcast era. The hardest-hit postseason homer and the hardest-hit ball in Phillies history, per Statcast? Schwarber’s homer against the Padres' Yu Darvish in Game 1 of the 2022 NLCS. He hit that ball into the second deck in right field at Petco Park at 119.7 mph.

“It was 117?” Stott said about Schwarber's latest feat on Monday.

“Is that how hard it was?” Castellanos said. “Wow. That was really hard.”

It was a heck of a way to open a series. The Phillies are 22-7 (.759) all-time in Game 1s, which is the best winning percentage of any team in MLB history (minimum 20 games). In all best-of-seven postseason series, teams winning Game 1 have won the series 121 of 188 times (64 percent). In series with the current 2-3-2 format, teams taking a 1-0 lead at home have won the series 65 of 97 times (67 percent).

“I feel like my favorite part of every home game is the first pitch thrown,” J.T. Realmuto said about Schwarber. “Because you can see he’s either right on something or the pitcher is scared to throw in the strike zone. Either way, it sets the tone.”