KANSAS CITY -- It didn’t take long for Matt Chapman to flex his newfound “Dad Strength.”

Back in the lineup for the first time since the birth of his first child -- a daughter named Gia Alexandra -- Chapman went deep twice as part of a five-homer day for the Giants, who routed the Royals, 9-0, at Kauffman Stadium on Saturday. San Francisco has now won two consecutive road series over American League Wild Card contenders (Baltimore).

• Every Dad Strength home run since 2011

“I’ve seen guys hit a lot of homers on the first day they’re back from having a baby, so I’m glad I got to join that club,” Chapman said.

LaMonte Wade Jr. also launched a pair of solo shots off Kansas City right-hander Brady Singer to collect his second career multihomer game and first since July 25, 2021. Chapman went back-to-back with Wade to extend the Giants’ lead to 3-0 in the fourth and then cleared the fences again to jumpstart a six-run rally in the sixth, giving him a team-high 26 homers on the year.

It marked the first time the Giants have had two players slug multiple home runs in the same game since June 11, 2023, when Thairo Estrada and Joc Pederson hit two homers apiece.

Mike Yastrzemski capped the power display with a three-run blast off Carlos Hernández that broke the game open in the sixth. The five homers matched a season high for the Giants, who also accomplished the feat on April 13, 2024, at Tampa Bay.

“I think guys are just really clicking right now,” Wade said. “I think the offense has definitely improved these last couple of series, which is a really good sign. I just think guys are not throwing in the towel. Everybody wants to come out here and win. We’re disappointed in how the year went and how we’re not going to make the postseason, but that doesn’t mean we can’t finish strong, and that’s what guys are doing right now.”

Like fellow rookie right-hander Mason Black on Friday, Landen Roupp picked up his first MLB win after spinning five scoreless innings in his 22nd career appearance and third start. Roupp leaned almost exclusively on his signature sinker-curveball combination to limit the Royals to three hits while walking three and striking out three.

“I kind of wanted it to come a little earlier than the end of the season, but it came and I can’t be happier about it,” Roupp said of his first win.

The 26-year-old now has a 0.89 ERA with 28 strikeouts over 30 1/3 innings in 11 outings since being recalled from Triple-A Sacramento on Aug. 9, which should put him squarely in the mix for a spot in the Opening Day rotation next spring.

“He’s really focused out there,” manager Bob Melvin said. “He’s intense. All of this is kind of building up with confidence. You’re seeing the type of stuff he has and what he can accomplish.”

It’s hard to imagine anyone having a better month than Chapman, who welcomed his daughter only two weeks after signing a six-year, $151 million extension that will keep him in San Francisco through the 2030 campaign. Chapman flew with the Giants to Baltimore on Monday, but he ended up making an unexpected detour to Arizona after his wife, Taylor, went into labor and gave birth to Gia on Wednesday.

Chapman missed four games while on paternity leave, but he did his best to get up to speed after flying into Kansas City around 12:30 p.m. on Saturday. He took ground balls at third and got some swings in before the game, though he said it was a little difficult to settle back in after experiencing a whirlwind of emotions this week. By the fourth inning, though, Chapman managed to fulfill a promise he made to his newborn daughter before leaving home.

“I left and told her I was going to hit a homer for her, so the fact that I hit a homer was exciting,” Chapman said. “I was just thinking about her when I was running around the bases.”

Wade added: “That was impressive. I think he’d been gone for the last five days. To come back and not skip a beat is pretty impressive. I think ‘Dad Strength’ is real.”

No Giants hitter has produced a 30-homer season since Barry Bonds in 2004, though Chapman could have a shot at ending the drought if he continues to tap into his “Dad Strength” and crushes another four homers over the club’s final seven games of the regular season.

“You’re going to have to go on a [Shohei] Ohtani run right there, but that is definitely something I’m aware of, that nobody’s done it since Barry,” Chapman said. “It would be awesome. But I’m going to have [seven] cracks at it. So I just want to keep playing well and finish the season strong and set the tone for us going into next season. I expect big things out of us.”