KANSAS CITY, Kan. — There was a time not so long ago that the U.S. Open Cup was an afterthought, a nice trophy to win for a Major League Soccer club but nothing compared to the league's MLS Cup.

That's not how Sporting Kansas City and the New York Red Bulls have treated it.

And perhaps more than any other reason, that's why the two teams will meet Wednesday night to decide the nation's oldest ongoing soccer competition.

Three-time champion Sporting KC and the Red Bulls, who lost in their only other finals appearance, have fielded some of their strongest lineups throughout the single-elimination competition. That's a stark contrast to many other MLS clubs, which have often fielded backup lineups to keep their top players fresh for the league schedule — especially against lower-division teams in the early rounds.

"When I first came to Red Bulls, I was aware of the fact that this organization and many of the managers here had not always taken this tournament seriously," New York manager Jesse Marsch said. "When I came here, this was going to be something that we emphasized, and we've played a lot of good lineups in my three years here and this year we managed to survive four tough games."

Indeed, neither Sporting KC nor the Red Bulls were given any free passes.

The charm of the U.S. Open Cup is that, along with the MLS clubs, it includes teams from the North American Soccer League, the United Soccer League and top amateur leagues. While none of those clubs has won the title since 1999, they occasionally pick off a few MLS clubs along the way.

That can produce an easier road for other MLS clubs to the finals.

But Sporting KC had to knock off Minnesota United, the Houston Dynamo, defending champion FC Dallas and the San Jose Earthquakes to reach the finals. New York beat New York City, the Philadelphia Union, New England Revolution and USL powerhouse FC Cincinnati to reach the championship match.

"We only played MLS teams, so we knew the matches would be very tough. We had to be prepared for them," said Sporting KC manager Peter Vermes, who led his club to titles in 2012 and '15. "I think anybody goes into this competition with everything they have. The games are very difficult."

There was another reason Vermes largely played his top guys, though.

"Our players need to get to a place where they can play three games in a week," he said. "Your main guys need to be able to play on a regular basis. So it's something we worked toward in the offseason, making sure we were in a position to play that way."

It's not as if the two clubs don't have designs on winning the MLS Cup.

Sporting KC, which will host the final at Children's Mercy Park, is currently third in the Western Conference and would comfortably be in the MLS playoffs. The Red Bulls sit sixth in the Eastern Conference and would also squeak into the bracket.

Yet to choosing to focus on one competition was never an option for Marsch or Vermes, who share a similar vision entering the season: There are three major trophies up for grabs, including the Supporter's Shield given to the MLS club with the best regular-season record and the MLS Cup itself.

The U.S. Open Cup would be the third one.

"We've viewed this in many ways," Marsch said. "I think it's really solidified what we're doing with our season, and our success has given our team confidence it can win in big situations."

Especially for the Red Bulls, who have never won the trophy.

Sporting KC hoisted the U.S. Open Cup in 2004, then won twice more in the past six years. But the club then known as the MetroStars lost 1-0 to the Chicago Fire in the 2003 finals.

"I think in this age, you see more teams playing their regular lineups," Marsch said. "We played a lot of MLS teams as well, and every MLS team played their full lineup. That made for some really difficult games. But I think our team understands this is a real trophy. This isn't just a throw-out tournament."