WASHINGTON -- D.C. United's MLS Cup playoff push continues on Sunday afternoon as the San Jose Earthquakes visit RFK Stadium for the latest in United's long sequence of must-win matches this month.Fresh off their most thorough win of the season, Thursday's 3-0 CONCACAF Champions League victory against CD Marathon -- which head coach Tom Soehn called "more of a complete performance than we've had in a while" -- D.C. is looking to build further momentum with another strong performance. The league's helter-skelter playoff picture allows United no margin for error as they continue to cling to a wild card berth, however, so snaring the full three points remains the paramount goal."There's not too many games left in the season and we need to take full advantage of each one, especially these home games," said Clyde Simms on Friday. "The win last night hopefully can spark a little streak."From United's perspective, one of Thursday's most encouraging developments was the two-goal haul delivered by star striker Luciano Emilio. The Brazilian is counted on to provide a substantial chunk of his team's scoring, but his form has run hot and cold this season. An inability to finish several first-half chances against Marathon suggested that he was stuck in the latter category, but his doggedness was amply rewarded in the second 45 minutes."Us forwards, we have a lot of pressure every game. But I think after today, I recovered a little bit of my confidence and I have more motivation for playing on Sunday. It's very positive," said Emilio afterwards. "It's going to be very good for me for the rest of the season."The Earthquakes are one of the few MLS clubs with limited postseason prospects, but they remain eminently capable of playing the spoiler role. Last week Frank Yallop's squad gave the playoff-chasing Rapids all they could handle in back-to-back matches and Colorado was lucky to escape with two 1-1 draws, finding late levelers after trailing for long stretches."They might be out of the playoffs but individually as players, they're playing for spots and for contracts," said Simms of the Quakes. "So they'll definitely be fighting, scrapping -- it's still going to be a tough game for us."United hope to avoid such complications by attacking their West Coast guests right from the outset. The Black-and-Red have typically looked more comfortable playing with a lead this season, although their first meeting with the Quakes was a glaring exception as D.C. squandered a 2-0 lead in San Jose and had to settle for a 2-2 tie."We just need to play our game," said Simms. "They're a team that's been struggling this season and if we jump on them early, maybe they'll start doubting themselves a little bit and hopefully the game will go our way."D.C. plays three more league games, and one more CONCACAF match, at RFK this season before finishing the campaign with road ties at Kansas City and Mexican side Toluca. Just as their 2004 predecessors used a late-season run to propel themselves toward an MLS Cup triumph, this year's squad hopes to surge into the latter stages of both domestic and international competition with the wind at their backs."We've got a little streak of games at home in the league and in Champions League," said Simms. "I feel like towards the end of the season, it's all about who's playing well at that moment. That determines how well teams do in MLS Cup. So that's something that we're looking to do."