Minnesota United's changes made to its back line Wednesday delivered a shutout and scoreless draw with streaking L.A. Galaxy after the Loons allowed seven leaky goals in two previous games.

Sunday afternoon's meeting with formidable D.C. United presents the chance to stay the same or change again, with veteran defender and captain Francisco Calvo back available to play. He and teammate Jan Gregus each served a one-game suspension Wednesday.

"We've got a few decisions to make," United coach Adrian Heath said. "We've got some work to look at and analyze and see if that's the best way to go."

With Calvo suspended, Heath opted to make other changes to his back four against Los Angeles. He started Brent Kallman at center back and sent Michael Boxall, who admittedly erred on Toronto's winning goal the game before on April 19, to a substitute's spot.

Heath welcomed back Ike Opara after missing a game with an injury. He also played Eric Miller for the first time this season, out of necessity, at Calvo's left-back position.

After making what Heath deemed repeated individual mistakes in a 3-3 tie with NYCFC and a 4-3 loss at Toronto, his defense and team made few, if any, against the Galaxy and star Zlatan Ibrahimovic.

After scoring seven goals in his first five games, Ibrahimovic had a season-low three shots — one of them on goal — after Opara and Kallman pushed him away from the goal and the far post where he likes to lurk.

"We didn't make the big mistakes that cost us the last two games," Heath said. "At this level, you get punished for that. We didn't gift them anything. They had to earn every little chance, which was pleasing. … We always talk about 'Don't beat yourself, make the opposition beat you.' Apart from Zlatan's header in the first half and maybe a couple half-chances in the second half, we kept a really good team down to minimal chances.

"I thought the back four did a really good job."

Opara's size and presence helped in his return, after he suffered a 7-inch gash over one eye late in the game against NYCFC in Allianz Field's debut. He credited what he called "trust" among a new back line configuration willing to learn and stick together.

"He's big, he's a big player for us," said United goalkeeper Vito Mannone, whose shutout was his second this season. "We all know we missed him in Toronto. It's good to have him back because he's a big presence. He can fight and he can win headers against tough strikers."

Miller, who hadn't played a minute in the season's first seven games, played all 90 minutes. Veteran midfielder Kevin Molino made his first start back from last season's knee surgery and played 61 minutes while Abu Danladi played 87 minutes as well.

Miller, of Woodbury, adjusted to Galaxy midfielder Uriel Antuna's speed on a right wing that L.A. tried to exploit all game.

"He had a tough task, and he did a good job," Kallman said. "He made a good adjustment at halftime and stopped getting too tight to him. There were no problems over there in the second half."

Kallman praised the six teammates in front of his four-man back line for United's consistent defensive shape and performance in a game that, in Heath's estimation, it deserved to win.

"It wasn't necessarily the back line doing a ton different," Kallman said. "The guys in front got in good spots and made it hard for them to break our line.

"Any time the guys in the front six do a really good job, it makes it way easier for the guys in back. I thought we did really well, really locked in, in really good spots, especially around the box. I think everyone locked in the entire game."