Brad Evans and Alejandro Moreno battle in midfield.Sounders FC are two victories away from winning the U.S. Open Cup for the fourth consecutive time, an accomplishment without equal in the 99-year history of the country’s oldest ongoing national soccer competition.There are two distinct paths to the title, but both start tonight at Starfire Sports Complex in Tukwila as the Sounders take on Chivas USA (7 p.m., live video stream on SoundersFC.com; 97.3 KIRO-FM) in the semifinals. Seattle and Chivas battled to a 1-1 draw in Carson, Calif., back on May 26, but the setting and stakes are far different. Seattle carries a 16-0-1 U.S. Open Cup record over the past three years into tonight’s match, outscoring its opposition 39-10. The Sounders have not lost a competitive match at Starfire since joining MLS in 2009.If this matchup seems familiar, that’s because it is: Seattle also faced Chivas in the semifinals two years ago at Starfire, winning 3-1 and earning the right to face Columbus in the final, as Fredy Montero scored the eventual game-winner on Steve Zakuani’s second assist of the night. James Riley, a fan favorite in Seattle for three years, lined up at right back for the Sounders that night, but he’ll be on the other side of the ball tonight after being selected by Montreal in the expansion draft, then dealt to Chivas. Midfielder Peter Vagenas, who was here the first two years, will suit up for Chivas as well.Then playing in the A-League, the Sounders also eliminated Chivas from Cup competition in 2007 and 2008, their final two years before joining MLS.The Sounders enter on an emotional upswing: Saturday night, they ended a franchise-record nine-match winless streak that stretched back to mid-May with a 2-1 home victory over Colorado. The match featured the uplifting return of Zakuani, who entered as a late substitute and saw his first action since suffering a severely broken leg against the Rapids last April, as well as Alvaro Fernandez’s first goal of the year and Eddie Johnson’s team-leading eighth, his fifth in his past six matches. Both were set up by perfect passes from Mauro Rosales, the first on a corner kick, the second on a cross into the box. Rosales, who leads Seattle with six assists, has set up half of Johnson’s goals.Seattle played perhaps its best match of the year just to make it here, traveling to San Francisco two weeks ago and knocking off Western Conference-leading San Jose 1-0 in the quarterfinals despite fielding a patchwork lineup dominated by reserves. Nineteen-year-old rookie Cordell Cato’s 19th-minute goal, his first as a Sounder, stood up as the defense came up huge in an physical, contentious match that spun out of control in the fading minutes and after the final whistle sounded, with Johnson throwing a punch in the middle of a melee in front of the Earthquakes’ bench.Chivas’ road to the semis began up the coast, where they edged the Ventura County Fusion of the USL’s Premier Development League 1-0 in a third-round match. The fourth round was cross-country in Cary, N.C., against the North American Soccer League’s Carolina RailHawks, which had stunned the defending MLS champion L.A. Galaxy the previous week. Chivas won 2-1 on Juan Pablo Angel’s penalty kick in second-half stoppage time. Another team from North Carolina was the quarterfinal opposition, and it took more late heroics from Chivas to defeat the USL Pro Division’s Charlotte Eagles, again by a 2-1 score, in Fullerton, Calif. Nineteen-year-old Colombian striker Jose Correa scored both goals, with the winner coming deep into second-half stoppage time after Charlotte had tied the score in the 89th minute. Chivas, coming off a scoreless draw at home against Vancouver on Saturday, is third from the bottom in the West–10 points behind the Sounders, who have played two more matches–but the Goats have been a difficult team to beat lately, with just one loss in their past 11 matches, including U.S. Open Cup play. Chivas has been especially tough on the road, battling two of the league’s best, San Jose and New York, to 1-1 draws. The key to Chivas’ recent success has been a stingy defense, with veteran keeper Dan Kennedy riding a 228-minute shutout streak.This will be the Sounders’ eighth match in the past 26 days, their fourth in the past 12, and there’s no rest; Seattle’s at New York on Sunday, the sixth road match of this stretch. Seattle has played three times since its Cup quarterfinal; Chivas–which doesn’t play until next Wednesday, at home against Portland–has played just once since its quarterfinal. Those contrasting schedules will have a lot to do with who plays tonight, and who starts.Expect to see Brad Evans, who didn’t play Saturday, and Cato, who entered in the 81st minute vs. Colorado, starting in midfield, along with a well-rested Servando Carrasco, who hasn’t played since July 1 at New England, and the tireless Ozzie Alonso, who sat out May’s draw at Chivas serving the first of a two-match suspension.Left back Leo Gonzalez and right back Zach Scott sat out against Colorado, as did center back Jhon Kennedy Hurtado–all three should be in a position to go the full 90.Forward Sammy Ochoa has started all three Cup matches this year and done well, scoring twice. With Johnson having played all but 18 minutes in the past three matches, Ochoa could pair up front with Montero, who entered in the 72nd minute against Colorado, sat out 10 days ago at New England, and should be well-rested. Or Sigi Schmid could go with versatile veteran Roger Levesque, who started and went all the way against San Jose and has been in these situations before: going back to 2007, this will be Levesque’s sixth consecutive Cup semifinal in a Sounders uniform. No matter who’s trying to score for Seattle, it will be a difficult task against Chivas, which has given up one fewer goal than the Sounders. The Goats’ defense, which was plenty tough already, got a major boost in mid-May when they pried one of the league’s top central defenders, Danny Califf, away from Philadelphia. Califf, imposing and physical at 6-2, 185, has played every minute of every MLS contest since coming to California, and Chivas’ defense has three shutouts in those seven matches, winning twice with four draws. The 10-year veteran has experience in big matches, scoring the extra-time goal that won the U.S. Open Cup final for L.A. in 2001, then anchoring a championship-caliber defense the following year as the Galaxy hoisted the MLS Cup.Chivas’ problem all season has been offense: they’ve scored just 11 goals, five less than any other MLS team, scoring more than once just two times, and been shut out on eight occasions. Angel, their leading scorer, has just three goals; only two other Goats, Correa and midfielder Alejandro Moreno, have scored more than once. Forward Juan Agudelo, another 19-year-old Colombian who scored against the Sounders in May on a header off a cross from Riley, is unlikely to play tonight due to swelling in his left knee, which was operated on in March to repair a torn meniscus. If the Sounders win, the path to the Cup will go through either Seattle or Kansas City. Philadelphia, the Eastern Conference’s second-worst team, hosts Sporting Kansas City, tied with D.C. United for the lead in the East, in tonight’s other semifinal. If the Union wins, the final would be Wednesday, August 8, at CenturyLink Field. If Sporting advances to the final, it would be August 8 in Kansas City. Both teams have played in Seattle this season. The Sounders beat Philly 1-0 in early May–before Saturday, the most recent home victory–and battled Sporting KC to a rough, ill-tempered 1-1 draw last month.