SAN DIEGO -- Kyle Higashioka understands the gig. When the game is late and close, and he’s due for a big at-bat, well … sometimes he doesn’t get to take that big at-bat.

“I’m no stranger to getting pinch-hit for,” Higashioka said with a laugh. “You know, if I hit like [Fernando Tatis Jr.], I wouldn’t.”

Indeed, for much of the season, the Padres have typically pinch-hit for Higashioka late in games. But with Tuesday’s game against Oakland tied in the bottom of the ninth inning, they entrusted their ninth-hitting backup catcher with the game’s decisive moment.

And did Higashioka ever deliver. He launched a walk-off solo home run into the first level of the Western Metal Supply Co. building in left field, sending the Padres to a dramatic 4-3 victory over the A’s at Petco Park.

“He’d more than earned his at-bat,” said Padres manager Mike Shildt, alluding to Higashioka’s recent hot streak at the plate. “Good for him. He’s done a nice job for us in both phases. And he’s got some pop.”

No kidding. Oakland reliever Scott Alexander hung a 2-2 changeup over the outer half of the plate. Higashioka turned on it, and sent a 103.9-mph rocket into the seats -- his first career walk-off home run and his second walk-off hit of any kind.

“That’s kind of the last thing that was going through my mind, especially with a high ground-ball guy,” Higashioka said. “Usually, you get too big against those guys, you end up just pounding it into the ground. We definitely just needed a baserunner. Luckily, he hung the changeup, and I just stayed through it.”

Added Shildt: “Big moment at Petco. That was fun.”

Much-needed, too. The Padres had given away a lead in the eighth inning when Oakland’s Tyler Soderstrom launched a game-tying, two-run homer off right-hander Enyel De Los Santos. Shildt revealed after the game that setup man Jeremiah Estrada was sick and had been sent home and thus was unavailable.

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In the bottom of that inning, outfielder Jurickson Profar exited the game after he swung and missed at a pitch and grabbed his knee. Shildt would later say that Profar has been battling knee soreness for a while and that the injury was not overly concerning.

Still, the Padres had taken a couple of late punches in a game they’d led since the fifth inning. In the ninth, Higashioka punched back.

“It was, overall, kind of a dicey game,” Higashioka said. “They were having a lot of good at-bats, and they had a lot of traffic, especially early. … We were all upset about losing the lead late like that. But this team just shows so much resilience, day in, day out.”

Higashioka arrived as perhaps the least heralded piece in the five-player package the Padres received when they traded Juan Soto to the Yankees in December. A light-hitting, defense-first catcher, Higashioka struggled even more than usual at the plate to start the season. He entered June with a minuscule .380 OPS.

But the Padres love his work behind the plate, and he’s found a niche in backstopping Matt Waldron and his dancing knuckleball. Lately, too, Higashioka has begun to hit, and he’s seen an uptick in playing time as a result. In five games this month, he’s hitting .353 with four home runs.

“He’s a great person,” right-hander Randy Vásquez said through interpreter Pedro Gutierrez. “On a personal note, he’s been able to help me out with my gameplan, just trying to execute whatever we have planned for that particular day. And he’s been a great teammate for me the last few years.”

Vásquez, who came over with Higashioka in the Soto trade, allowed a leadoff home run to Abraham Toro and plenty of baserunners after that. But he deftly navigated it and settled in to pitch five innings of one-run ball.

Tatis -- as red-hot as Higashioka alluded to -- extended his hitting streak to 17 games with a first-inning single. That’s the longest active streak in the Majors and halfway to Benito Santiago’s franchise record of 34 games set in 1987.

The Padres grabbed a 3-1 lead in the fifth inning, scoring three runs with four consecutive two-out hits -- on four consecutive pitches, no less. It was Profar’s two-run single that put the Padres on top.

Late drama ensued before Higashioka, the unlikeliest of heroes, ended it.

“A huge swing for him and for us,” Shildt said. “That’s a big win. That’s a nice ballgame. A good win all the way around.”