FC DALLAS AT SOUNDERS FC7 p.m., Starfire Sports Stadium, Tukwila.TV/RADIO: None. The game will be streamed live at SoundersFC.com.NOTES: This is a semifinal match of the U.S. Open Cup, the U.S. Soccer Federation’s national championship, which is open to allamateur and professional soccer teams affiliated with U.S. Soccer. The tournament began in 1914 and is the oldest annual team competition in U.S. sports. … The winner advances to the final Oct. 4 against the winner of the Chicago Fire-Richmond Kickers (USL-Pro) match, also tonight. If the Sounders advance, the final will be played at CenturyLink Field. … The Sounders are two-time defending Open Cup champions. They are trying to become the first team to win three straight since Greek American SC of New York did it from 1967-69 … These are two of the top three teams in the MLS regular-season standings: Seattle is 13-5-9; Dallas is 13-7-7. The clubs have split their two regular-season meetings: The Hoops won 1-0 on May 25 in Seattle, while the Sounders won 1-0 on Aug. 20 at Dallas. … Rookie Josh Ford is expected to be Seattle’s reserve keeper as Terry Bosshas been called in by the Puerto Rico national team. …The game is sold out.QUOTABLE: “We have always taken the Open Cup seriously. Obviously Dallas takes it seriously as well, because Lamar Hunt was their original owner and the Hunt family still owns the team. I think it’s a game of massive importance.” – Sounders coach Sigi Schmid.NEXT: 1 p.m. Sept. 10, Real Salt Lake; CenturyLink Field.