PHILADELPHIA -- The best part of Kyle Schwarber’s home run in the first inning on Opening Day was not the sound it made when it left his bat. It was not the ball slamming off the billboard hanging from the second deck in right field at Citizens Bank Park. It was not the raucous reaction from the sellout crowd.

It was not Schwarber’s spirited curtain call.

It was Schwarber, only a step or two after bashing that ball in his first Phillies plate appearance in a 9-5 victory over the A’s on Friday afternoon, looking into his dugout and casually raising his right index finger. It looked like he was telling them that it was the first homer of many he plans to hit this season. His teammates roared.

Schwarber swears it wasn’t that, though.

“My heart rate was going about 150 mph,” Schwarber said, smiling. “I don’t know why I did that at all. I just did it. It was just adrenaline and things like that going. If I hit another one, I probably won’t do it.”

So, no No. 2 when he hits his second?

“No,” he said. “I didn’t know what was going on. I was just kind of floating out there.”

In the end, it doesn’t matter. It was a fun, spontaneous moment on a day Phillies fans had been waiting for since the team signed Schwarber to a four-year, $79 million contract, and Nick Castellanos to a five-year, $100 million deal in March.

“How do you like the new guy?” Rhys Hoskins said. “That's just stuff you talk about. You joke about it. You can't hit a first-pitch homer if you don't swing at the first pitch. You can't hit a homer in your first at-bat if you don't swing the bat.”

Schwarber worked a one-out walk in the third inning to spark a four-run rally, advancing from first to third on J.T. Realmuto’s single to right and scoring on Bryce Harper’s double to left-center field to make it 2-0.

Schwarber hit .266 with 32 home runs, 71 RBIs and a .928 OPS in 113 games last season with the Nationals and Red Sox. But his 17 homers, .385 on-base percentage and 1.216 OPS in 27 games leading off also caught the Phillies’ eye. Their leadoff hitters had an abysmal .302 on-base percentage last season, which ranked 29th in baseball.

It was why Harper hit with runners in scoring position in only 18.5% of his plate appearances, which tied for the 185th-lowest mark out of 4,605 players with 125 or more plate appearances since 2008.

Harper will have more opportunities with Schwarber in the lineup.

“He had great at-bats today. He saw a lot of pitches,” Harper said. “He never gives up an at-bat. I think one through nine, I thought the lineup flowed really well. I thought it looked really good.”

“It is kind of what we imagined,” manager Joe Girardi said.

The Phillies turned a 6-1 lead into a one-run game in the seventh, but they kept adding. The final blow: Schwarber’s two-out single to right-center in the eighth to make it a four-run game.

Schwarber went 2-for-4 with one home run, one walk, two RBIs and two runs scored in his Phillies debut.

“I couldn’t write it any better for myself,” he said.

Schwarber might have played with some newfound dad strength on Friday. The night Schwarber and the Phillies agreed to a deal on March 15, his wife, Paige, went into labor. She gave birth the next day to their son, Kade.

Schwarber left home in Ohio for Spring Training in Clearwater, Fla., on March 20. He had not seen his family until he flew home for about 12 hours following Wednesday’s Grapefruit League finale against the Rays in St. Petersburg.

“Get a little rejuvenation before the season starts,” Schwarber said. “It was good for everyone. It was good for me. It was good for my wife, and good for him, to just kind of get back up there. They’ll be joining us whenever we get off the road, but it was definitely nice to go up there and see him again.”

One day he can tell Kade about his Opening Day in Philly. Or maybe he will just show him a highlight or two, index finger and all.

“To start like that, what a way to introduce yourself,” Hoskins said. “That's him. We love it. But none of us are surprised.”