PORTLAND, Ore. (AP) — Eric Wynalda seemed genuinely surprised. After celebrating his amateur team's upset of the Portland Timbers, the Cal FC coach was beckoned by a group of reporters.

"You're waiting to talk to me?" he asked.

Wynalda, like many of the fans gathered at Jeld-Wen Field on Wednesday night, was shocked by Cal FC's 1-0 overtime victory over the Major League Soccer club in a third-round match of the U.S. Open Cup.

After all, he only assembled his team in February and up until a few days ago they were wearing old Chicago Fire castoff kits. The team, a hodgepodge that includes a few former MLS players, had practiced just once in the week leading up to the match.

These fellas, Wynalda explained, have day jobs.

Cal FC, based in Thousand Oaks, Calif., became the first U.S. Adult Soccer Association team to score against an MLS club in a U.S. Open Cup match. In 2006, Dallas Roma defeated Chivas USA on penalty kicks to advance to the fourth round, where the team fell to the Los Angeles Galaxy.

"Expectations with this group? They keep surprising me," said Wynalda, the former standout for the U.S. national team. "I don't know how to describe it, they are just an amazing group of kids."

Artur Aghasyan, who played for a time last year with Real Salt Lake, scored in the first overtime for the win. He charged Portland goalkeeper Troy Perkins in the 95th minute and chipped the ball into the goal as Perkins slid on the turf.

Within moments after the 120-minute match, "Cal FC" was trending worldwide on Twitter. Wynalda was amused.

"I don't know what to tell you guys," he said. "I'm a little bit taken aback by all of this."

Cal FC defeated the Kitsap Pumas of the USL Premier Development League and the USL Pro's Wilmington Hammerheads in the first two rounds of the 99-year-old tournament. With the victory over the Timbers, the team moves on to face the Seattle Sounders in a fourth-round match next Tuesday in Tukwila, Wash.

Portland was left embarrassed.

"There's no excuses for tonight. No excuses whatsoever," coach John Spencer said. "We should come here, we should win the game. I don't think we should win the game easy, but I don't think we should lose the game. Not at all. Totally unacceptable."

The Timbers took the match seriously, using many of their regular starters, including Scottish striker Kris Boyd. They took 37 shots, but none found the net.

Portland's Darlington Nagbe fired the ball from atop the box in the 23rd minute, but it was scooped up by goalkeeper Derby Carillo. Eric Alexander also had a chance in the 42nd minute, but his shot just skimmed over the crossbar.

In the second half, sub Brent Richards and forward Jorge Perlaza got off three threatening shots, but all went over the bar.

But the crowd was most stunned when Boyd's penalty kick in the 80th minute also sailed over the top.

As the minutes wound down, the Timbers Army supporters' group chided their team by chanting: "Care like we care!"

"Everybody in the forward areas need to have a look at themselves, and we must score," said Boyd, the Scottish Premier League's all-time leading scorer before coming to the Timbers this season. " When you have that many chances in a game, you've got to score goals. It's as simple as that. It's impossible to have that amount and not score."

Cal FC celebrated on the pitch at Jeld-Wen long after the match. The team posed for pictures and even bowed to the Timbers Army, which had chided them mercilessly during the match.

In the end, Portland's fiercely loyal supporters showed their admiration by applauding the upstart amateurs and imploring them to beat the rival Sounders.

Seattle defeated the NASL's Atlanta Silverbacks 5-1 Wednesday night to advance.

The fourth round poses some new challenges for Wynalda, who played in three World Cups as a forward for the U.S. national team from 1990-2000. Like coming up with a place to practice.

"We have limited resources and not the money (the Sounders) do. Finding a place to train is something we look for because we're right in the middle of something special, and we want to make sure we're prepared," he said.

The U.S. Open Cup is a single-elimination tournament open to all U.S. Soccer affiliated teams, from the amateur to the professional level.