The Lamar Hunt U.S. Open Cup returns to action tonight with the quarterfinal round. Of the four matches, only one is an all-MLS matchup.

Let's look at all four matches and see who plays who and where for the semifinal round.

San Jose Earthquakes (MLS) at Seattle Sounders (MLS)

Site: Kezar Stadium, San Francisco, CA.

Time: 10:30 p.m. ET

The Seattle Sounders have won the last three U.S. Open Cups, so you know they will be taking this match seriously, something MLS clubs are not known for, with a few exceptions. They are trying to become the seventh team to win four or more cups, but the first to win them all consecutively.

The Sounders will be looking to bounce back from a 2-1 loss to their bitter rival Portland Timbers on Sunday in Portland. They are in fourth place in the Western Conference of MLS, winless in their last seven league matches.

Seattle's last cup match was a 5-0 win over Cal FC, but they were the last amateur side left in the tournament, assembled about a month-and-a-half before the match by former US international Eric Wynalda, and they had already beaten Portland. Cal FC held Seattle scoreless in the first half.

The San Jose Earthquakes would be the second team from San Jose to win the Cup. In 1992 (before the start of MLS), the San Jose Oaks won the cup.

The Earthquakes used a 2-1 road victory over Real Salt Lake on Saturday to leapfrog over RSL into first place in the Western Conference, three wins in their last four matches.

Prediction: San Jose will attempt to use the quasi-home field advantage to knock a tired, struggling Seattle team out of the tournament. San Jose wins 2-1.

Charlotte Eagles (USL Pro) at Chivas USA (MLS)

Site: Titan Stadium (Cal State Fullerton), Fullerton, CA.

Time: 10:30 p.m. ET

The Charlotte Eagles are sitting in ninth place in USL Pro. Their last league match resulted in their first home win of the season and they've struggled to score in league play, tallying 13 goals in 13 games.

Charlotte, however, has won three straight Open Cup matches against teams from Texas, including a 2-0 third round victory over MLS side FC Dallas. They have also had a week to rest their players.

CD Chivas USA are in seventh place in the MLS Western Conference. They've had a harder time of scoring goals than Charlotte, notching only 11 goals in their 14 league matches.

Chivas will be facing their second straight opponent from the state of North Carolina, having defeated the Carolina Railhawks in the fourth round. They are also playing their fourth game in 11 days. Their last match was a scoreless draw against FC Dallas.

Prediction: Charlotte will show no fear going up against another MLS side, having already defeated one. Charlotte wins 2-1.

Harrisburg City Islanders (USL Pro) at Philadelphia Union (MLS)

Site: PPL Park, Chester, PA.

Time: 7:30 p.m. ET

The Harrisburg City Islanders currently stand in seventh place in USL Pro, the third division of soccer in the United States. They're coming off of a 2-1 road loss to the second-place Charleston Battery on Saturday. Harrisburg is also the highest USL Pro team left in the competition, all three of which are in the bottom half of the table.

The City Islanders, though, in the David v. Goliath nature of the tournament, have already slain a couple of giants. In the fourth round, they used extra time to beat the New York Red Bulls 3-1. That was after they produced a dramatic comeback to even get that far.

Harrisburg trailed a 10-man New England Revolution side 3-0 in extra time. They scored three goals in a period of nine minutes to tie the match and then won it on penalties.

The Philadelphia Union find themselves in ninth place in the ten-team Eastern Conference and have only three league wins on the season in 13 matches. However, they are also coming off that third win, a 4-0 home thrashing of potential semifinal opponent, Sporting Kansas City.

Philadelphia will be in their third game under interim head coach John Hackworth and trying to build off Saturday's win, as well as their extra-time victory over conference leaders DC United in the fourth round.

Prediction: Harrisburg's Cinderella story will find the clock has struck midnight. Philadelphia wins 2-0.

Dayton Dutch Lions (USL Pro) at Sporting Kansas City (MLS)

Site: LIVESTRONG Sporting Park, Kansas City, KS.

Time: 8:30 p.m. ET

The Dayton Dutch Lions are in 10th place in USL Pro, having only one league win so far this season, a 4-0 home win against the Wilmington Hammerheads. Those four goals represent almost half of the nine goals Dayton has scored in 13 league matches.

The Dutch Lions, however, have already beaten an MLS side in this tournament, defeating the in-state Columbus Crew 2-1 in the third round.

Sporting Kansas City are sitting in third place in the MLS Eastern Conference, one point out of first. They are coming off their worst loss all season, a 4-0 defeat to Philadelphia.

After the game, defender Aurelien Collin tweeted, "Hey SKC I wanna apologize for this game it was embarrassing . Now let's go back to kc and rest well and prepare for the next one..."

Sporting KC has, however, already beaten USL Pro frontrunners Orlando City and a fellow MLS side, the Colorado Rapids, in their Cup run so far. They are making the tournament a priority and should have All-Star defender Matt Besler back after his appendix was removed just over two weeks ago.

Prediction: Sporting KC uses a full-strength starting XI and an enthusiastic home crowd to send Dayton home. Sporting KC wins 2-0.

Potential Semifinals

Semifinal 1

If Seattle defeats San Jose, they will host the winner of the Charlotte-Chivas USA match at the Starfire Sports Complex in Tukwila, WA, at 10:00 p.m. ET on July 10th.

If San Jose defeats Seattle, they will host the winner of the Charlotte-Chivas USA match at Buck Shaw Stadium, Santa Clara, CA, at 10:30 p.m. ET on July 10th.

Semifinal 2

If Philadelphia defeats Harrisburg, and Sporting KC beats Dayton, Philadelphia will host Sporting KC at PPL Park, Chester, PA, at 7:30 p.m. ET on July 11th.

If Philadelphia defeats Harrisburg, and Dayton beats Sporting KC, Philadelphia will host Dayton at PPL Park, Chester, PA, at 7:30 p.m. ET on July 10th.

If Harrisburg defeats Philadelphia, and Dayton beats Sporting KC, Harrisburg will host Dayton at the Skyline Sports Complex, Harrisburg, PA, at 7:30 p.m. ET on July 10th.

If Harrisburg defeats Philadelphia, and Sporting KC beats Dayton, Sporting KC will host Harrisburg at LIVESTRONG Sporting Park, Kansas City, KS, at 7:30 p.m. CT on July 10th.

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