LOS ANGELES -- Fernando Tatis Jr. didn’t sleep very well on Saturday night. Hours earlier, he’d been hit by a pitch in the left elbow, and he felt pain every time he moved. The Padres’ rookie phenom arrived at Dodger Stadium on Sunday morning unsure whether he’d be able to play. An hour before first pitch, Tatis was given the green light.

He suited up just in time to make some history.

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Tatis led off the game with a line-drive home run to straightaway center field. Four innings later, he crushed a three-run shot into the left-field pavilion. On the strength of those two blasts, the Padres finished their first half with a 5-3 victory and their first winning four-game series in Los Angeles in 15 years. They’re back to .500.

Tatis, 20, became the youngest player in history to go deep twice in a game at Dodger Stadium. (Scott Rolen had done so as a 21-year-old in 1996.) He’s also the youngest Padres hitter to record a multihomer game, surpassing the previous mark set by a 22-year-old Cesar Crespo in 2001.

“You don't take his talent for granted,” said Padres first baseman Eric Hosmer. “It's incredible what he does. You forget his age in all that. It's amazing.”

The Tatis family, of course, has a history with Dodger Stadium. It’s where Fernando Tatis Sr. famously hit two grand slams in the same inning (months after Tatis Jr. was born in 1999). The younger Tatis said he hadn’t been to Chavez Ravine since he was a kid traveling with his father. He missed the Padres’ first trip here in May while battling a hamstring strain.

"It's amazing," Tatis said of his record-setting afternoon. "Especially here, in this park, where my dad hit the two grand slams. That's a lot of history for our family."

Tatis Jr. and Sr. became the first father/son combo with multihomer games in the same ballpark since Barry and Bobby Bonds did so at Shea Stadium. But strangely enough, neither of Tatis Jr.’s homers qualified as his most dazzling highlight on Sunday.

With two outs in the second inning, Austin Barnes hit a grounder up the middle. Tatis went full-extension and gloved the ball before crashing to the turf. From his left knee, he flung a perfect sidearm throw to first baseman Eric Hosmer to retire Barnes.

“He had one of his best games of the year,” said Padres manager Andy Green. “A diving play, very consistent in the field, two home runs, big swings for us -- and he was less than 100 percent.”

It was the perfect cap to Tatis' other-worldly first half. He missed all of May with a left hamstring strain (likely costing him a spot on the National League All-Star team). But when he’s been on the field, he’s done a little bit of everything. That’s why the Padres waited so long on Sunday morning to submit their lineup.

“It's probably debatable whether he should have four days off coming up,” said Green, taking a subtle dig at Tatis’ All-Star snub. “But he's got four days off. Everybody in this clubhouse wanted to see him out there. However much time we needed to give him [this morning], we got that thumbs up.”

After his surprise inclusion on the Opening Day roster, Tatis has been every bit the five-tool player the Padres have dreamed of since they acquired him in the James Shields trade three years ago.

With a 2-for-4 showing on Sunday, Tatis finished his first half hitting .327/.393/.620 with 14 home runs. He’s been a human highlight reel on the bases, and he owns the five hardest throws Statcast has tracked by a shortstop this season.

On Sunday, Tatis worked a six-pitch at-bat against Dodgers starter Ross Stripling before swatting a fastball 415 feet to center field. In the fifth, manager Dave Roberts called for righty Pedro Baez, preferring to avoid a Tatis-Stripling matchup again. It didn’t matter. Tatis crushed another homer, this time on a belt-high 95-mph heater.

“Tatis showed how good he is and what competing against him for the next six years is going to look like,” Stripling said.

Three days ago, the Padres’ season felt as if it might be teetering. They’d lost five straight games, including a home sweep at the hands of the last-place Giants. A daunting task loomed in the form of a four-game set at Dodger Stadium this weekend.

Instead, the Friars took three of four, and they’ll enter the All-Star break at .500 or better for the first time since 2010.

“We showed what we were capable of, how we're moving, what we can do,” Tatis said. “So pay attention. It's going to be interesting.”

It already is. There’s a palpable sense of optimism in San Diego, and the budding superstar at shortstop might be the biggest reason.