In sifting through replacement options, Coach Ben Olsen took into account both Acosta’s void and the Chicago Fire’s potency. If the looming threat of German superstar Bastian Schweinsteiger and Co. is swaying his opinion, Olsen is likely to take a defensive posture in central midfield with Marcelo Sarvas as the top candidate to join Ian Harkes and Jared Jeffrey.

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A long-shot possibility: Olsen christens defensive midfielder Chris Durkin, who has been training regularly with the first team since returning from U.S. under-17 national team duty. Olsen said Friday that Durkin would be in uniform for the first time.

United needs to begin generating more scoring chances, but also prevent Chicago’s influential middle from overrunning it.

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“We tossed around a few different ideas,” Olsen said. “Some of the conversations are about how we can increase our output offensively, but some of it is also how we can deal with one of the better central midfield combinations in the league. That’s a tricky balance.”

A defensive-tilted midfield would put greater onus on United’s flanks to create opportunities. Lloyd Sam and Lamar Neagle have started in the wide positions the past four matches. Patrick Mullins, searching for his first goal of the year after recovering from a hamstring ailment, is the probable starter up front.

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Acosta’s absence comes at a terrible time. United (3-5-2) went scoreless in losing consecutive home matches against one-win teams and doesn’t have anyone to match his skill set. He is also the team’s top scorer with three goals.

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United has gone scoreless six times and posted nine goals overall — one fewer than Chicago striker Nemanja Nikolic, the league leader in his first year in MLS.

Nikolic ($1.9 million) was not the only marquee acquisition by Chicago, which missed the playoffs six of the previous seven years and watched attendance and enthusiasm dwindle at Toyota Park. Schweinsteiger ($5.4 million) arrived from Manchester United one month into the season and made a profound impact, providing guidance, organization and a few goals.

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The Fire (5-3-3) arrived in Washington on the heels of two impressive displays over five days: a 4-1 rout of 2016 champion Seattle and a 3-0 victory over Colorado. With a third match in a week, Chicago Coach Veljko Paunovic seems likely to make lineup changes.

United has been trending in the opposite direction. After an encouraging road swing, D.C. lost to Montreal and Philadelphia on consecutive weekends at RFK. A heavy load of early home matches figured to work to United’s advantage this spring. Instead, D.C. is 2-3-1 with four goals, a minus-five differential and four scoreless efforts.

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After hosting Chicago, United will play seven of nine on the road.

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Aside from Acosta’s slot, Olsen will need to address the right side of the back line as Sean Franklin (hamstring) and Nick DeLeon (hernia surgery) remain out.

Last week, captain Steve Birnbaum, a natural center back, filled in while Kofi Opare partnered with Bobby Boswell in the middle. This week, Olsen might consider Chris Korb, who is back in the mix after missing 20 months with knee problems. Korb entered in the 53rd minute last week.

“No doubt, it’s an important game,” Olsen said. “It’s a fine balance of anxiety and panic. We have a good gauge of that. … It’s important for our senses to be heightened and our urgency to be elevated, but understand that it’s a long season.”

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United notes: D.C. will face an amateur team, Baltimore’s Christos FC or Chicago FC United, in the fourth round of the U.S. Open Cup on June 13 or 14 at Maryland SoccerPlex, the U.S. Soccer Federation announced. … United is 5-0-4 in the past nine regular season meetings with Chicago. … Referee: Hilario Grajeda. … Game-time weather: 69 degrees, partly sunny, light wind.

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D.C. United vs. Chicago Fire

Where: RFK Stadium.

When: Saturday at 4 p.m.

TV: UniMas, Univision Deportes.

Records: United 3-5-2, 11 points; Fire 5-3-3, 18 points.

D.C. probable starters: GK Bill Hamid; Ds Steve Birnbaum, Bobby Boswell, Kofi Opare, Taylor Kemp; MFs Lloyd Sam, Marcelo Sarvas, Jared Jeffrey, Ian Harkes, Lamar Neagle; F Patrick Mullins.