The Union are 2-1 after a 1-0 road loss to the Los Angeles Galaxy on Saturday. D.C. United are 1-2.
"Anytime you can play or compete for another piece of hardware for the trophy case, it's important," Union assistant coach John Hackworth said Tuesday regarding the U.S. Open Cup.
Hackworth said midfielder Justin Mapp, who missed Saturday's game with a strained hamstring, was back working out with the team.
Later, the team announced it had surpassed the 12,000 season tickets sold during its inaugural 2010 season.
Najar to play for Honduras. Reigning MLS rookie of the year Andy Najar of D.C. United will represent Honduras - instead of the United States - in international play.
The 18-year-old midfielder announced his decision during a news conference Tuesday at RFK Stadium, where United play their home games.
Najar is from Honduras and went to high school in Virginia. He has a green card and eventually will be eligible for U.S. citizenship.
He had five goals and one assist in 26 MLS games with United last season, when he became the youngest player to win MLS rookie honors and the first to come directly from the youth-academy level. United signed him from their youth ranks in March 2010.
This article contains information from the Associated Press.
Contact staff writer Marc Narducci at 856-779-3225 or firstname.lastname@example.org.