Ben Olsen and D.C. United are looking forward to the 2016 MLS regular season opener against the Los Angeles Galaxy on Sunday night at StubHub Center. (Nick Wass/Associated Press)

CARSON, Calif. – D.C. United redesigned the midfield and attack over the winter, bidding farewell to three longstanding figures, adding six fresh options and changing a veteran’s role.

And as the 2016 MLS regular season dawns, Coach Ben Olsen’s task is to make it work.

“They are all great pieces,” he said. “How do we solve the puzzle?”

Olsen’s defensive unit is set and his goalkeeping options are clear while Bill Hamid recovers from knee surgery. The rest of the lineup will take shape as the campaign unfolds, beginning Sunday night against the Los Angeles Galaxy at StubHub Center.

Chris Rolfe and Fabian Espindola, the leading scorers the previous two seasons, will be on the field, but is Rolfe on the front line or the wing, and will Espindola continue to have the freedom to roam? How will Nick DeLeon embrace the transition from the flank to the middle?

Marcelo Sarvas was acquired from Colorado to both fill the defensive midfield chores left behind by Perry Kitchen (now in Scotland) and inject the leadership lost by Davy Arnaud’s retirement.

Patrick Nyarko and Lamar Neagle arrived from Chicago and Seattle, respectively, to run the flanks. Neagle, who is also a forward, is eager to make his debut; he sat out the two-leg CONCACAF Champions League quarterfinals because he had played in the tournament with the Sounders last fall. He fills the role left by Chris Pontius, United’s longest-serving player, who was dealt to Philadelphia.

There is more for Olsen to consider: What to do with Markus Halsti, the Finnish national team player whose first season in Washington last year went largely unnoticed, and Alvaro Saborio, the club’s only natural striker nearing the end of a fine career?

Olsen will also want to integrate rookie Julian Buescher, who scored a sensational goal Tuesday in the Champions League; second-year wing Miguel Aguilar; and newcomer Rob Vincent, a starter Tuesday.

And then there is Luciano Acosta, the exciting Argentine import. He is a natural playmaker sitting in the heart of the attack, but during the two Champions League matches, he played beneath the lone forward, Espindola. The Boca Juniors products have begun to forge an understanding.

“We’ve got to figure out a way to get him the ball more because he’s going to be one of those guys that can take over a game on his own,” captain Bobby Boswell said of Acosta. “The minute you start getting worried about him, you have to worry about our other weapons. He’s going to hurt you or someone else will.”

Over the course of an eight-month, 34-match season, Olsen will need all of the options. No team relies on the same starters every weekend; United used more than 25 different combinations last year. With salary cap space, United has hinted at adding another piece in the coming months, as well.

United is counting on the new elements to raise the danger level of an attack that scored multiple goals in three of the last 13 matches last season, including the playoffs.

“With each game we try it, we get further along in our ideas of who we are,” said Olsen, who is entering his sixth full season as head coach, the longest tenure in club history. “Until the games come and you see this stuff live, it’s tough to do in training.”

The Galaxy is also adapting to change. Bruce Arena is blending three European signings – England’s Ashley Cole, Netherlands’ Nigel de Jong and Belgium’s Jelle van Damme – with a returning corps that includes Ireland’s Robbie Keane, England’s Steven Gerrard, Mexico’s Giovani dos Santos and American Gyasi Zardes.

Like United, the Galaxy was ousted from the Champions League on Tuesday, a 4-0 setback at Mexico’s Santos Laguna. United showed greater promise than the Galaxy in the international competition, though against a lesser opponent (Mexico’s Queretaro).

“There is a lot of good to take out of it,” United left back Taylor Kemp said. “It is going to give us momentum going into the season. We’re ready for it.”

United notes: The club is finalizing a contract with Andrea Mancini, a 23-year-old Italian forward who was in training camp for six weeks. The former Manchester City prospect most recently played in Hungary. His father, Roberto, coaches Inter Milan, owned by United’s chief investor, Erick Thohir. … Defender Kofi Opare was cleared to play after missing extended time with headaches. … United has not beaten the five-time champion Galaxy in Carson since July 2005, an eight-game regular season stretch (0-4-4).

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D.C. United at Los Angeles Galaxy

Where: StubHub Center in Carson, Calif.

When: Sunday at 10 p.m. ET.

TV: UniMas.

D.C. probable starters: GK Andrew Dykstra; Ds Sean Franklin, Bobby Boswell, Steve Birnbaum, Taylor Kemp; MFs Patrick Nyarko, Marcelo Sarvas, Nick DeLeon, Luciano Acosta, Chris Rolfe; F Fabian Espindola.

L.A. probable starters: GK Dan Kennedy; Ds Ashley Cole, Jelle Van Damme, A.J. DeLaGarza, Robbie Rogers; MFs Emmanuel Boateng, Nigel de Jong, Steven Gerrard, Giovani dos Santos; Fs Gyasi Zardes, Robbie Keane.