Audi Field opened in July with an MLS match between D.C. United and the Vancouver Whitecaps. (John McDonnell/The Washington Post)

Audi Field was built primarily to house D.C. United, but the 20,000-seat soccer stadium in Southwest Washington was also designed to stage other events.

And in its first major score outside MLS competition, the venue’s management reached an agreement in principle to host a U.S. men’s national team friendly in June, multiple people familiar with the selection process said Tuesday.

The opponent has not been secured yet by the U.S. Soccer Federation, which has scheduled games for June 4 or 5 and June 9 in the buildup to the Concacaf Gold Cup, which begins June 15. The U.S. team’s opener is June 18 at the new MLS stadium in St. Paul, Minn.

Cincinnati, which will have an MLS expansion team this season, is the favorite to host the other U.S. friendly, said the people familiar with the situation, who requested anonymity because they were not authorized to speak publicly. If FC Cincinnati’s current home, Nippert Stadium, is selected, natural grass would have to be installed over its artificial turf.

Per policy, the USSF declined to comment on the venue search while negotiations continue, but a spokesman said the governing body is aiming to announce its choices in a few weeks.

The U.S. men last appeared in Washington in October 2016 for a 1-1 draw with New Zealand at RFK Stadium. No venue in the country has hosted the men’s squad more times than RFK, but with Audi Field’s opening last summer, the new venue has sought to attract international matches.

RFK remains in the mix: On March 26, it will host a friendly between Peru and El Salvador. And FedEx Field will continue to seek large-scale matches, such as the annual International Champions Cup, featuring elite clubs from around the world.

Audi Field was not selected for the Gold Cup, in part because the complex has just three locker rooms, one short of what’s needed for the tournament’s doubleheaders in the group stage and quarterfinals. For stand-alone matches, though, it is a fresh option for soccer promoters and the USSF, which uses both large NFL stadiums and smaller MLS venues for men’s and women’s matches.

The men’s team will play friendlies next month at MLS stadiums in Orlando and Houston. The women’s team will not play in Washington in the buildup to the World Cup this summer in France but could end up at Audi Field during a post-tournament tour.

Audi Field hosted two non-United soccer events last year: a Washington Spirit women’s match and a Maryland-Virginia NCAA men’s game.

United is close to finalizing a deal to play a friendly against Spanish club Real Betis either after La Liga’s season ends in May or June or before next season begins in July or August, a person close to the negotiations said. Betis is eighth in the league race and in the round of 32 in the UEFA Europa League. Its roster includes Mexicans Andres Guardado and Diego Lainez, though the timing of the match could prevent their participation.

The Spirit, based at Maryland SoccerPlex in Montgomery County, could play two matches at Audi Field this summer. An XFL team will call it home in 2020, and stadium officials have been in talks about staging lacrosse, rugby and concerts.