Sporting KC got its first goal off a restart after midfielder Graham Zusi found the head of substitute Jacob Peterson in the 65th minute. Peterson's header somehow managed to lift over goalkeeper Zac MacMath, who was planted near the post, just one of the few mental blunders he has made this season.
Zusi later capped the night in stoppage time, scoring from midfield on a long shot that beat MacMath, who had pushed up high with the rest of his teammates in search of an equalizer.
But MacMath, the Union and the 8,486 on hand could only watch as the team's aspirations to reach the Open Cup final were dashed with one long shot.
"I think we made too many mistakes and they just took advantage," Union captain Carlos Valdes said. "For some moments of the game, we looked confused, and we couldn't connect a lot of passes basically in the last part of the field. When you play like this in a game as important as a semifinal, you pay a lot for your mistakes. And we definitely did tonight."
In all, there were 38 fouls between the teams (21 for the Union, 17 for Sporting KC) and enough off-color language among the players to warrant a parental-advisory label on the webcast.
"I think beating them, 4-0, really didn't do us any good, because they came out and played us real physical," forward Jack McInerney said, referring to the teams' MLS meeting last month. "Their strengths are playing balls in the box and using their size, and they did both tonight. There were a couple scuffles here and there, but we had to keep our composure because being down a man and a goal would have been stupid."
Sporting Kansas City awaited the winner of the later game between Chivas USA and three-time defending Open Cup champion Seattle. Should Chivas knock off Seattle, Kansas City will host the final on Aug. 8 or 9.
"We knew they wanted to be in the final as much as we did, and so we needed to bring it just a little bit harder," Sporting KC coach Peter Vermes said. "We had a game plan, and I am proud of my guys for sticking to it for the entire game. I thought there were some moments there where we weren't playing attractive, but I think we finished well."
The Union had a solid defensive first half, but, for the first time since John Hackworth became inteim manager, it was a half devoid of any offensive wave. Sporting KC goalkeeper Jimmy Nielsen easily snuffed out any scoring chances. The second half, however, was a different story, as the Union, desperate for a goal, spread the pitch and attacked.
Chances came — and went. The two greatest came from rookie substitute Antoine Hoppenot and midfielder Freddy Adu. In the 69th minute, Hoppenot broke into the box and ripped a shot cleared by Nielsen for a corner. In the 89th, a feed from defender Amobi Okugo found Adu near the post. Instead of slotting a ball across the box to onrushing defender Sheanon Williams, Adu blasted a shot over the bar, which summed up a night of frustration.
The Union was looking to become the first Philadelphia-area club to qualify for the U.S. Open Cup final since the Walt Bahr-led Ukrainian Nationals captured the title in 1966, capping a string of four titles in the 1960s. A trip also potentially meant an appearance in next year's CONCACAF Champions League campaign, the winner ticketed for the FIFA Club World Cup.
The Union has little time to dwell on the Open Cup exit, however, as it returns to MLS action against expansion Montreal on Saturday. Next Wednesday, the Union open its slate of international club exhibition matches against English Premier League club Aston Villa.
"There is no room for a letdown; we have an important match against Montreal on the weekend, and we need to keep the league momentum going that really started in the Open Cup [against D.C. United]," midfielder Brian Carroll said. "And it starts again on Saturday, and starts really tonight and tomorrow, recovering and getting ready to fight through this season."
Contact Kerith Gabriel at firstname.lastname@example.org. Follow him on Twitter @sprtswtr.