The most recent time Minnesotans could enjoy a top-league soccer match in an open-air stadium was nearly 40 years ago.

And apparently, the spirit of those northern soccer fans hasn’t changed much at all in all that time.

“Even when you lost, the fans were, ‘You know what, Tino? It’s OK. Tomorrow’s another day,’ ” former Minnesota Kicks goalkeeper Tino Lettieri recalled. “Wow, these people aren’t even mad that I let in a couple goals here.”

Lettieri and the Kicks drew crowds as big as 46,370 at Metropolitan Stadium in the late 1970s. New Major League Soccer team Minnesota United FC projects attendance to exceed 35,000 at 4 p.m. Sunday at TCF Bank Stadium when the Loons (0-1-0) take on fellow expansion side Atlanta United FC (0-1-0) in the team’s home opener.

But if the supporters’ reaction to a 5-1 loss at Portland to open the season last week was any indication, Minnesota fans have carried on that same compassionate nature through generations.

“I could see in the fans’ faces after a big defeat like 5-1, and they were still shouting us on, cheering us on, and I could feel the vibe in the whole city the whole week,” United captain Vadim Demidov said. “I’m not used to that.

“If we lose 5-1, I’m used to getting booed on after the game. So I feel like the crowd here is fantastic. I think they’re with the team no matter what, and the players really feel that. And I think we owe them after a bad result to have a good game at home.”

Eric Adamson, 48, of Lakeville, remembers going to a July 4th match at Metropolitan Stadium when the Kicks played the Connecticut Bicentennials. Then a kid growing up in Apple Valley, he has since lived across the country and spent time in Europe. Now, he and his wife, Kim, are eager United season-ticket holders.

“It’s been a dream of mine since we moved back to Minnesota in 2003 [from Oklahoma],” Adamson said. “Ever since then, I’ve wanted them to get a MLS franchise.”

Erin Bloxham, 43 of St. Paul, and Aron Kramer, 42 of St. Paul, are also season-ticket holders. Bloxham said she’s been a United fan since it played in the lower-division North American Soccer League in Blaine. She can tell the excitement level is much greater now in MLS, not only for the hometown team but also for fans to see high-level talent from around the league.

Atlanta, for example, has three designated players on its roster, a distinction for top talent commanding higher salaries. The team has made big-money investments seeking to make a big impact right from its first season.

“I was following all the stuff about Atlanta United and their opener, and I was totally jealous,” Kramer said. “I really hope we get to have something that exciting happen here.”

Atlanta opened its season at a temporary home — Georgia Tech’s Bobby Dodd Stadium — drawing a sellout crowd of 55,297, including 30,000 season-ticket holders. The team’s real home — Mercedes-Benz Stadium, shared with the Atlanta Falcons — opens in the summer.

The Loons have sold more than 33,000 tickets and expect to exceed 35,000. The team said it has sold more than 11,000 season tickets, near a cap of 11,842. However, Atlanta had more time to organize ticket sales than United, which could only begin that work after officially joining the league in August. Single-match tickets went on sale only a month ago.

Still, a 35,000-plus crowd will dwarf the 5,000 to 10,000 that United drew playing in the NASL. It would top the only time United played at TCF Bank Stadium in summer 2014, when United defeated Ottawa 2-1 on two Christian Ramirez goals. The Loons played after European clubs Manchester City and Olympiakos drew 34,047, and the crowd did thin out before United took to the then-badly reviewed pitch.

“They had the grass laid over the turf so the playing conditions weren’t that great,” said United left-back Justin Davis, who took in the match from the bench after not making it back into the lineup after a suspension. “But the atmosphere was cool. Not everyone stayed after the Man City-Olympiakos game, but there was still a good-size crowd. And I think everyone will be in full force on Sunday.”

The ironic part of the 2014 experience is that rainy and cloudy weather in August is what influenced many fans to leave the doubleheader early. Now, fans will brave below-freezing temperatures and possible snow in March to watch United at The Bank.

At least this time around, the players and coach Adrian Heath only had pleasantly surprised reactions to the turf pitch.

While the stadium will still have plenty of university maroon and gold decoration, United’s black and blue colors, plus its loon logo, will display on digital signage around the stadium. There will also be some physical banners, such as over the players’ tunnel. This nationally televised match also has the Gophers’ field markings temporarily painted.

Ramirez said TCF Bank Stadium is a “cool” environment because the fans feel like they are right above the players. While there might be pressure to live up to the standard Atlanta set in its home opener, Ramirez said the only real tension between the two new teams is about words instead of numbers.

“Maybe just they took ‘United’ as well,” Ramirez said. “Other than that, I don’t think [so.] … We’ll see what Sunday brings, if Atlanta brings a new rivalry.”

Heath, though, just wants his team to remember how historic and truly once-in-a-lifetime this opportunity is.

“The players are really excited,” Heath said. “I think everybody’s aware of how important this day is going to be. And I think also that everybody realizes that they have a responsibility, an obligation, to put on a really good show for everybody.”