TUKWILA — An unlucky bounce. A controversial call. A bad night.

Over the course of 18 U.S. Open Cup games, surely something had to go wrong and lead to a Sounders defeat. The unpredictable nature of elimination games isn't supposed to lead to such sustained success.

Instead, Seattle improved to a staggering 17-0-1 all-time in the Open Cup (including qualifiers) with a 4-1 semifinal win Wednesday against Chivas USA. The Sounders will go on the road to play Sporting Kansas City for the championship on Aug. 8.

So does coach Sigi Schmid ever take a step back to reflect on the special run his team has had in the knockout-style tournament?

"I'll take a step back and think about it after Aug. 8," he said with a smile after Wednesday's semifinal triumph.

"When you look at what these guys have done in one-off games, and you look at the history of any league around the world, you don't see any teams winning four straight FA Cups (in England) or Copa del Reys (in Spain) or stuff like that. Teams might win four league championships in a row, but because there are so many things that could go wrong in a one-off game, it's tough to win four in a row."

History in the world's leading soccer countries confirms what Schmid said in principle, but not quite exactly.

In the major knockout-style tournaments in England, Germany, Spain, Italy and France, only two teams have ever won four in a row. Both came decades ago in Spain's Copa del Rey: Real Madrid (1905-08) and Athletic Bilbao (1930-33).

While the Sounders look forward to a fourth straight Open Cup final, one player will remarkably be preparing for his fifth. Midfielder Osvaldo Alonso, who leads the team with four goals this tournament, also advanced to the final in 2008 with the Charleston Battery of the United Soccer Leagues.

Alonso had a goal and assist Wednesday, including a cheeky chip to convert a penalty kick. He has scored winning goals in three of the team's four Open Cup games this year.

"Five in a row ... I'm very happy for that," said Alonso, who was voted Seattle's team MVP the past two seasons.

On the heels of a nine-game league winless streak, the Sounders are 3-0-2 in their last five against MLS opponents, including two wins in the Open Cup. Schmid credited much of that recent success to Alonso.

"I've really thought over the last three games or so that Ozzie has really taken a step forward," the coach said.

Gspurning will travel to New York

Goalkeeper Michael Gspurning, who has missed the last 12 MLS games with a hip strain, will travel for Sunday's 1 p.m. road game against the New York Red Bulls. His role, however, is yet to be determined, Schmid said Thursday.

"I feel ready to play... but what we do in New York is up to the coach," said Gspurning, who boasts a 0.46 goals-against average, which leads the league among goalkeepers with more than one start. "I'm just happy to be on this trip."

NOTES

• Sounders general manager Adrian Hanauer told KJR Radio on Thursday that he expects the U.S. Open Cup final will be broadcast on the FOX Soccer Channel.

• Sporting Kansas City defender Aurelien Collin, who was recently named to the MLS All-Star First XI, will be suspended for the Open Cup final due to yellow-card accumulation.

• Ticket sales have reached 49,000 for Wednesday's friendly against English club Chelsea FC, the reigning UEFA Champions League winner. Tickets are available on SoundersFC.com or by calling 1-877-MLS-GOAL.

Joshua Mayers: 206-464-3184 or jmayers@seattletimes.com.

On Twitter: @joshuamayers