The US Open Cup field has been whittled down to eight, meaning it's time for the quarterfinals, with plenty of intrigue in store.

Six MLS teams are still in contention, alongside the upset-minded Carolina RailHawks and Orlando City SC, both of whom have beaten MLS opposition twice to reach this stage.

MLSsoccer.com will have full coverage of the matches, including a live chat with updates and reports from the matches. In the meantime, here's a roundup preview to get you prepared for what could be a wild night of action.

D.C. United vs. New England Revolution, 7 pm ET

A scoreless draw against New England during the MLS campaign kicked off the current spirited run by D.C. United (seven points in four matches across all competitions), so it's only fitting that D.C. will meet the Revs with even more on the line in Wednesday's quarterfinal round of the Open Cup at the Maryland SoccerPlex in Boyds, Md.

With so much emphasis being put on the Open Cup by United's coaching staff and players, Ben Olsen rested captain Dwayne De Rosario – who scored a hat trick in United's 3-1 Open Cup win against Philadelphia – for the club's 1-0 victory against San Jose on Saturday in the hope that he'll be at full strength against New England.

Said midfielder John Thorrington, who wore the armband with De Rosario on the bench Saturday: "The Open Cup is one of two trophies that we’re in this year and it’s huge for us. ... We actually enjoy going out and playing there [at the Soccerplex]. It’s a different kind of atmosphere and hopefully we’ll reward the fans that come out there again on Wednesday with a positive result and keep advancing."

New England head coach Jay Heaps will have several lineup choices to make in Maryland, with a continuing flight to Los Angeles scheduled ahead of Saturday's match at Chivas USA meaning the Revs are traveling with a large squad.

Despite the presence of several starters in the mix, Heaps is once again expected to rely on players pressing for first-team minutes – including the likes of Kalifa Cissé, Andy Dorman, Ryan Guy, Matt Reis and A.J. Soares – to shepherd the Revs through this tricky test and into a semifinal tie at Chicago or Orlando on Aug. 7.

"Our focus is really one game at a time," Heaps said. "We know we're playing D.C. on Wednesday. They are a tough group. Our focus is 100 percent on trying to advance in the Open Cup. As a group, we've prepared for this game. I want my players knowing that it will take a lot more guys over the next stretch of games. At the same time, if we begin to look ahead, there's a problem there. We are focusing 100 percent on Wednesday. We understand the turnaround. We'll be prepared." — Nick Cammarota & Kyle McCarthy

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Chicago Fire vs. Orlando City SC (USL PRO), 8:30 pm ET

Frank Klopas is taking the US Open Cup seriously – the Chicago Fire head coach made that much clear when he didn't start Patrick Nyarko and Jeff Larentowicz against the Columbus Crew on Saturday.

Klopas will almost definitely start his first choice 11 on Wednesday against Orlando City in the US Open Cup quarterfinals, though. Nyarko will be back on the outside, with Dilly Duka possibly starting on the opposite wing after staking a claim to the spot with a strong week. Larentowicz and Alex will likely round out the midfield.

“Looking at a team that beat KC, it's not going to be an easy game, the guys know that,” Klopas said. “The guys are preparing from a mental standpoint to accept a difficult opponent. We're not taking this lightly by any means.” — Anthony Zilis

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FC Dallas vs. Portland Timbers, 9 pm ET

The five international-player limit in the Open Cup rules will force FC Dallas head coach Schellas Hyndman to make changes to his lineup and means a likely opportunity for backup goalkeeper Chris Seitz to build on the 180-plus-minute shutout streak he has going in this edition of the tournament.

“[The previous shutouts] puts him in a great position," Hyndman said after Tuesday's practice. "That and we also want him to get games and these are good games to get."

Hyndman indicated Ramon Nuñez could also see significant playing time after impressing in his performance last Saturday against Sporting KC.

And though Dallas' lineup may change somewhat, both teams will still be plenty familiar with each other. Just 11 days ago, Portland beat Dallas 1-0 in MLS play – their second meeting of the season – and recently supplanted them atop the Western Conference standings.

With that in mind, Timbers head coach Caleb Porter said after the team’s training session Tuesday in Dallas that the team will take the game seriously, despite it being their eighth game in the last month.

“The league is very important, but I’ve said from the beginning we’re not really prioritizing one over the other,” Porter said. “We want to make the playoffs and we want to push for the Supporters’ Shield. But we want to make a run in the Open Cup, and we have a chance to win a trophy. We’re now three games away.” — Matt Barbour & Dan Itel

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Real Salt Lake vs. Carolina RailHawks (NASL), 9:30 pm ET

RSL head coach Jason Kreis will once again trot out a lineup laden with first-choice players, though Devon Sandoval, who has been a star in Open Cup play so far, may be the one exception. Regular starting midfielders Kyle Beckerman and Javier Morales have been on the pitch in the last two USOC games and are likely to be there again, so don’t expect anything less than a full effort from the hosts.

And with the semifinals slated to be held at the winner of this game’s home field, Real know they have a golden opportunity to win the tournament and grab a coveted spot in the CONCACAF Champions League.

RSL could get a pretty good scouting report on the Carolina RailHawks from midfielder Enzo Martinez, who went on loan with the second-division side earlier this season, appearing in three games and scoring a goal. The Claret-and-Cobalt could certainly use all the information they can get their hands on, too, as Carolina currently sit atop the NASL standings and knocked off the LA Galaxy and Chivas USA to reach the quarterfinal stage.

“We know every team once you get this far can play,” said RSL defender Tony Beltran. “Just because they are a lower level, there is no excuse to overlook them. They are hungry to show they can play at this level.” — Michael Black

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