This is the equivalent of the Phillies' playing a team from a South Jersey men's league in a single-elimination tournament.

That's what it will be like Tuesday night when the Union host the Ocean City Nor'easters in a Lamar Hunt U.S. Open Cup game at PPL Park.

The U.S. Open Cup pits soccer teams of all levels, amateur to professional. Ocean City is an amateur team from the USL Premier Development League. In 2009, Ocean City lost to D.C. United of Major League Soccer, 2-0, in the U.S. Open Cup.

Now Ocean City is playing another MLS team, but this game has more significance. That's because it is a pro team from its own backyard.

"It will be great to play at PPL Park and play the Union," said Ocean City midfielder Ken Tribbett, who plays for Drexel. "I've watched games but never played there."

Ocean City has won two games in this year's Open Cup; this will be the first Cup match for the Union.

Tribbett and his teammates are not entering this game with blinders on. They realize the Union are a prohibitive favorite.

"We will play as hard as we can and hope for a David vs. Goliath result," Tribbett said.

If Goliath doesn't do a better job of defending, who knows what can happen? The Union are coming off a 5-3 MLS loss Saturday in Montreal.

"Our defensive play wasn't very good," Union team manager John Hackworth told reporters afterward.

The Union play their next MLS game Saturday in Toronto, and they hope the leaks in the defense are plugged by then.

The MLS season takes precedence over the Open Cup. It's likely that many of the Union starters won't play the entire game Tuesday, if they play at all. The Open Cup is a way to get others involved, but the Union insist they aren't going to go through the motions.

Assistant coach Rob Vartughian said the Union would take a serious approach to the game. They scouted Ocean City's second-round 1-0 win over the visiting Pittsburgh Riverhounds, a team from the USL Pro Division.

"We had folks there at the game and will have a scouting report and the same pregame lead-up to any game," Vartughian said.

The Union also have the added incentive that no professional team wants to lose to an amateur squad, no matter how talented.

Ocean City has some standout college players and recent graduates who will be eager to show their skills against professionals.

The key from the Union's perspective is to get off to a quick lead because the longer the game is deadlocked, the more pressure the favorite faces.

Yet Ocean City can't have the attitude that it is just happy to be there, although that's easier said than done.

"It is extremely exciting," said Ocean City general manager Neil Holloway. "One of our major goals every year is to qualify for the U.S. Open Cup and get as far as we can."

The Union probably have a different goal: to get out of the game with no injuries. And to secure a win, denying bragging rights to an amateur club.

Contact Marc Narducci at mnarducci@phillynews.com. Follow @sjnard on Twitter.