By design, Allianz Field looms 70 feet tall on its south end, rising high above the already steep and forbidding "Wonderwall" in an architectural statement meant to separate it from the freeway and travelers bound for either Minneapolis or St. Paul directly behind.

It has also become, four months after its opening, something of a citadel all the way around for a Minnesota United team that calls it home.

Wednesday's narrow 1-0 victory over Colorado was its ninth shutout this season and its eighth at Allianz Field, where the Loons now are 8-1-4. Darwin Quintero scored a goal in the 39th minute, two minutes after he missed a penalty kick. That goal stood as the winner before a sellout crowd announced at 19,629 fans.

They Loons are now 12-8-5 overall and back in second place in the Western Conference, 14 whopping points behind first-place LAFC and six points away from missing the playoffs in the stacked West.

"We're comfortable here," United coach Adrian Heath said. "The crowd was magnificent again. They've been unbelievable since we opened this place, and the players have given them something."

Video (02:46) United coach Adrian Heath and goalkeeper Vito Mannone discuss Wednesday's 1-0 victory over Colorado.

This night, United offered an uneven yet resilient performance that could have been, should have been more than a one-goal victory. It also came precariously close to a tie and only one point gained.

"When you're hanging around at 1-nil, that's never enough," Heath said. "When you look back at the game and the chances we had, that should not be the case. You cannot leave teams hanging around. With the quality of chances we created this evening, the game should have been hung and dried."

And yet it went down to the final moments of second-half stoppage time, when Colorado goalkeeper Clint Irwin moved forward and became an 11th attacker for his team's last-gasp — and unsuccessful — corner-kick attempt.

"It was a game we needed to win," United veteran goalkeeper Vito Mannone said. "Let's say we took it home. In a certain way, it was probably not the nicest win, but sometimes you win games like this, especially at home. I've said it before: We grind wins, and this was another one."

Mannone himself grinded out that ninth shutout, despite taking a shot in his face in the second half after he challenged the shooter.

"I work for moments like this," he said. "If I don't come [out], it's an opportunity for him to score. It's important you show courage. It doesn't matter if you get kicked or not. I'm not that beautiful."

Heath rested eight starters for Saturday's 5-3 loss at Dallas so they could recover from an emotional U.S. Open Cup semifinal victory over Portland and to shelter them from a hectic schedule and the Texas heat. He brought them back Wednesday for the first of two home games this week that he considers crucial for a team that now has 41 points, nine shy of what Heath believes it will take to reach the playoffs.

"We're at that stage of the season now whoever you play, there's something to play for now," Heath said.

United has nine regular-season games left, four at home. "I love playing in this stadium," Mannone said. "I feel like there's an extra man in front of the goal."

Asked if he and his team are feeling unbeatable at home, Mannone said, "Well, you're never unbeatable. It takes one moment to slip.

"We're quite strong, yes. Unbeatable? You need to prove it and prove it and prove it and go until the end."