As Eldridge looked up at the TV screen, the calm mental resolve that helped shape him into one of the best high school athletes in the country turned to mush; he rubbed his eyes in a futile effort to hold back tears as MLB Commissioner Rob Manfred called his name at draft headquarters in Seattle.

Many scouts and fans had called Eldridge “the American Ohtani” for his two-way talents. On Sunday night, the Giants told him he’ll be given the opportunity to live up to that lofty billing.

“Everything that I worked for was leading up to this day,” Eldridge said. “It’s crazy. That day is here.”

When asked where the moment ranked in his life, he didn’t hesitate: “Number one.”

Eldridge told The Post he will forgo the University of Alabama after committing to the program as a freshman. He will sign with San Francisco, which made him the first high-schooler drafted in the first round out of Northern Virginia since the Baltimore Orioles selected Westfield’s Brandon Snyder with the 13th pick in 2005.

Westfield outfielder Jonny Farmelo, who battled Eldridge’s Warhawks five times this season, including in a state championship game that Madison won, went 29th to the Seattle Mariners.

“Me and him are going to share a phone call later,” Eldridge said. “He is a great kid.”

Hype had long swelled around the prospect of Eldridge as a major leaguer — no more so than in baseball-crazed Vienna, where many anticipated this night a decade earlier. Family members, teammates and coaches spoke of Eldridge in terms that toed the line between reality and hyperbole, claiming he hit three home runs when he was 10 less than a day after his idol, Bryce Harper, did (true), and that he hit a walk-off home run that bounced over to the Vienna water tower, more than 600 feet from home plate, when he was a sophomore (in dispute).

“Vienna has embraced him,” said his father, Ben. “You can see that tonight.”

Major league front offices took note of the towering star during his sophomore year as he and 2021 second-round pick James Triantos led the Warhawks to the state title. The noise only got louder over the summer between his junior and senior years, when Eldridge lifted the U.S. team to an under-18 Baseball World Cup championship and earned MVP honors for his two-way exploits.

This spring, scouts and fans came out in droves to see whether Eldridge could duplicate the act locally. He rewarded their faith. At the plate, he churned out a 1.750 OPS with nine home runs. On the mound, with a fastball that topped out at 97 mph, he went 11-0 with a 1.30 ERA and struck out 88 in 53⅔ innings. He was perfect in a relief appearance in the state title game, shutting out Westfield over the final three innings to deliver the Warhawks another state championship.

Less than two weeks later, he was named All-Met Player of the Year.

“I couldn’t have been here without all the support of these people around me,” Eldridge said Sunday.

He began the night with a balmy demeanor, laughing with teammates over the blaring televisions and background chatter, well aware his draft stock was in the middle-to-late part of the first round. When the Pittsburgh Pirates selected LSU’s Paul Skenes with the first pick, he and his teammates laughed and let out a playful “Aww!”

Heading into the draft, Eldridge had a sense last week the Giants could be his destination after he excelled during the pre-draft workout. Still, at No. 16, San Francisco was even higher than his mom, Beth Kenney, projected.

“I honestly didn’t think it was possible,” she said. “But he was hitting bombs. So we felt pretty good about our experience.”

Before pick No. 15, Eldridge went outside with his phone to his ear, with everyone in the restaurant craning their necks to get a feel for the call’s tenor. Eldridge kept a steely demeanor — the Giants had just told Eldridge that he “might be their guy” — before coming inside and motioning for everyone to calm down.

Several minutes later, he kept his phone to his ear and smiled.

The hugs and selfies lasted more than an hour after the selection. One relative pulled out a sheet of paper with every draft pick’s slot value and pointed to No. 16, which has a $4,326,600 valuation.

Still, challenges lay ahead. Though Ohtani has redefined what MLB front-office executives are willing to dream of, no other modern player has become a productive two-way major leaguer.

Last season, the Giants also used their first-round pick on a two-way prospect, Reggie Crawford. Still, Eldridge is entering rare territory. He welcomes it.

“The ballpark is beautiful,” he said. “They’ve got a great history, great farm system, such a great fan base — I mean, living out in San Francisco and playing baseball every day, that’s the dream.”