TUKWILA — Much of the U.S. Open Cup's appeal comes from the potential for dramatic, bracket-shaking upsets in "David versus Goliath" matchups. And no more is that the case than in a fourth-round game at 7 p.m. Tuesday, when Sounders FC hosts Cal FC at Starfire Stadium in Tukwila.

On one side there's Seattle — an MLS powerhouse and three-time defending Open Cup champion.

On the other is Cal FC — an amateur team featuring players with day jobs (e.g. parking valets, waiters) that was put together a few months ago by former U.S. men's national team star Eric Wynalda.

If the Sounders have become the Open Cup bully, then Cal FC is the tournament darling, having shockingly advanced through three rounds, including an astonishing road win last week in Portland.

Not your average amateurs.

"It's not a Sunday morning pub team," said coach Sigi Schmid of Cal FC. "It's not a bunch of guys who roll out of the bar and walk out onto the field to play. These are all guys who still see soccer in their future."

Three Cal FC players — Danny Barrera, Derby Carrillo and Jesus Gonzalez — have had tryouts with the Sounders in the past couple of years. Six or seven players, according to Wynalda, have standing offers from professional teams once their Open Cup run is over.

Playing professionally, however, is a team-wide aspiration.

"If these guys aren't with professional teams in August, then I didn't do my job," said Wynalda, who played in three World Cups and retired as the country's leading scorer (since passed by Landon Donovan).

It's not hard to get caught up in the endearing qualities of Cal FC. The team was reportedly set to wear old Chicago Fire uniforms until it ran the risk of forfeiture from the Open Cup. The group is tirelessly raising funds to keep up with travel demands and other expenses. Much has come from the pocket of Wynalda, who can also charm with his honesty and humor.

The Cal FC project has ultimately been so meaningful — and fun — that Wynalda has put his own dreams of being an MLS coach on hold.

"I'm going to continue to do what I do and ... help these kids who might need a second chance, and hopefully find a home for them," he said. "That's really what Cal FC is trying to do. It's not all these big broad statements that everyone would like to believe — that I'm out to prove the world wrong. It's just trying to do the right thing."

NOTES

• U.S. Soccer president Sunil Gulati told Soccer By Ives that Schmid's comments Sunday were "completely inappropriate and quite frankly offensive." Schmid said he felt the federation was rooting against his team and possibly working against it in the Open Cup draw. Gulati described any notions of a conspiracy as "nonsense."

Sounders GM Adrian Hanauer supported his coach in the want for more transparency in the draw, but tried to soften the blow of Schmid's comments.

"I know Sigi well enough to know that some of what he says is a little bit of jab, some of it's a little tongue-in-cheek, some of it is how he feels, but just because he says something doesn't mean that he believes 100 percent, for instance, the draw is rigged," Hanauer said.

• Goalkeeper Michael Gspurning has left the team and will seek a second opinion regarding his hip injury in California. The 31-year-old Austrian, who leads the league with a 0.43 goals-against average, has missed the past six MLS games.

• Limited tickets are available for Tuesday's game. FOX Soccer's video feed will be streamed on SoundersFC.com with Ross Fletcher and Alan Hinton providing commentary.

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

On Twitter: @joshuamayers