There was one thing left to test, and 24 minutes into U.S. Bank Stadium’s ballyhooed debut — staging an International Champions Cup match between two of the world’s super brands — the massive scoreboards in the Vikings’ new home got their first action.

Gooooooooooooal!

In front of a lively, sellout crowd announced at 64,101, Chelsea’s Bertrand Traore got his head on a rebound and sent the ball flush into the net, shrugging off AC Milan’s early control. The first goal of Wednesday’s milestone, in which Chelsea notched a 3-1 victory, sparked one of the night’s loudest moments. Fans leapt from their seats, waving flags and scarves, providing a taste of what the 66,200-seat structure might sound like after a touchdown this fall.

“This atmosphere [here] is very similar to England’s atmosphere,” new Chelsea coach Antonio Conte said after the match, adding that he thought the quality of the pitch was “very, very good,” particularly in comparison of his team’s previous game vs. Real Madrid in Michigan Stadium.

But as happy as the crowd was to be a part of the celebration, the reasons for showing up varied.

Some came to tour the state-of-the-art, 1.75-million-square-foot beauty, some came for a glimpse at some of the world’s elite soccer clubs, and some just to drink a few overpriced beers and have a good time.

A couple of early Milan misses — including a last-minute save by Chelsea goalkeeper Thibaut Courtois — got the masses going early, but while there wasn’t much of the singing or chanting native to international soccer, the crowd maintained a steady buzz throughout. The first wave began less than half an hour in, and the first goal was followed by a halfhearted rendition of “Olé!”

The crowd seemed heavy on Chelsea blue, but at least one fan hinted the club might have strategically stretched its base a little.

“It helps when they hand out free stuff,” said Katie Becker, 28, with a smirk. “We’re huge Chelsea fans now.”

After the AC Milan equalizer in the 38th minute, on a free kick from Giacomo Bonaventura, the energy only heightened. Nearly the full rosters of both teams saw the pitch, with both squads rolling substitutions and some of the team’s bigger stars, such as Chelsea’s Eden Hazard and Cesc Fabregas — who started — getting more raucous ovations. When Oscar scored Chelsea’s second goal on a penalty kick in the 78th minute and then tapped in the insurance score in the 87th, the stadium reached near fever pitch as Prince’s “Let’s Go Crazy” blasted over the speakers.

“Fantastica,” AC Milan coach Vincenzo Montella would say later of the stadium and atmosphere.

Before the teams took the field with the sunset visible in the background, the $1.1 billion monolith two years in the making slowly awoke.

Outside, the weekday downtown work crowd intertwined with jersey-wearing, flag-draped fans making their way to the maze of white-topped tents on the stadium’s bustling plaza.

“Wow, that is just gorgeous,” a woman exclaimed, her face angled upward toward the venue’s northwest face that reflected the skyline of downtown Minneapolis.

Just after the doors opened at 6 p.m. — just the human-size doors on this humid August day, not the five pivoting stadium-height doors — patrons trickled into the bowl of purple seats, clutching programs and cameras, grinning for selfies at the second tier overhang. But an hour before the game began, the massive crowd stilled circled the concourse, buying shirts at the Chelsea and AC Milan stands and promptly pulling them on.

The opening act to what the Vikings hope will be a party for years to come was about to begin.

“It’s big, it’s imposing, it just makes you excited to come to a game,” said Andrew Tri, 37. “The lighting is amazing. You look out here and you can see the sun poke through on the grass. It’s going to be a great place to watch Vikings games.”

Added wife, Emma, a lifelong Chelsea fan who had painted them both with eye “blue” via a cheap canister of makeup: “It looks expensive, too.”