Kasey Keller knows a thing or two about rivalries.
After all, the former Seattle Sounders goalkeeper played in more than a few during his decorated career, including an intimate glimpse at the Tottenham-Arsenal affair and a long look at West Ham-Millwall, rivalries played by teams just miles – make that kilometers – apart on the map in England.
But when describing what makes Seattle-Portland a rivalry that, well, rivals any in the world, Keller knows there’s something different about what’s at stake.
In short, it took work just to bring this rivalry back from life support at times throughout the years, and to make this modern incarnation one that resonates as the best in Major League Soccer.
"It's the history and the way the fans of both clubs have made a point to keep that history alive," Keller explains. "It could have died, but the fans wouldn't let it, through multiple incarnations, owners, leagues and franchises, Sounders-Timbers endured. That's special."
Chances are, when you tune in Sunday night for the latest installment of Sounders-Timbers (10 pm ET, ESPN2) it won't be the first time you've caught the spectacle. But with Clint Dempsey set to make his home debut – and his first-ever appearance in the rivalry – the volume has been turned up a notch, if that's possible.
A sell-out crowd of 68,000 will be in the stands at CenturyLink Field and a sizeable national television audience is also expected.
"There is always a buzz around town when it's a Portland week, not just on game day," says former MLS defender Craig Waibel, who played with the Sounders during the team's A-League days and is now an assistant coach at his alma mater, the University of Washington. "But since Clint was signed, it has become deafening."
The noise is not just coming from Seattle, but also from across the state line, where Timbers fans – at least not the hardcore Timbers fans – aren’t all looking at the Dempsey signing as something good for the league, or even good for American soccer.
"No, they're mad about it," says Keller. "And they already had a bit of a complex."
The signing of Dempsey, for a dollar amount that's been reported as the most ever for an American player in MLS, has ratcheted up the intensity of the already fervent Timbers Army, many of whom will make the trek to Seattle this Sunday. In no uncertain terms, Portland fans feel the team to the north is getting some preferential treatment.
Adin Brown, who played a couple of games for the Timbers in 2011 and now serves as a Timbers Alumni Ambassador and radio analyst, along with being a goalkeeping coach for the men's and women's teams at the University or Portland, says his adopted home city can’t help but feel like the little brother in a sibling rivalry.
“It's a smaller city. The team plays in a smaller stadium. It's a chip on our shoulder, I think,” he says. “Of course, Portland is known as Soccer City, USA, which says, 'Back at ya, Seattle.'"
Keller recalls the first time he played for the Sounders against the Timbers, in the 2009 Open Cup, when Portland was still playing in the USL.
"We were in MLS, but the Timbers fans at Civic Stadium (now the remodeled JELD-WEN Field) were not the least bit impressed," Keller recalls. "And they let me know it from the second I got on the field. But, I grew up in the Seattle area, so it didn't surprise me at all. I knew what I was getting into."
What Keller and Waibel point out, as guys born and raised in the Pacific Northwest, is that soccer has always been a well-respected sport, as far back as they can remember.
"I was one of the 'I told you so' guys when the Sounders started in MLS, and were playing consistently in front of huge crowds," says Waibel. "The love of the sport up here is off the charts. All that needed to happen is that it needed to be brought to the people.
“Of course, it helped that the Sounders were immediately a team to be taken seriously. Winning the US Open Cup in the first season was big. But I can tell you, even though the Sounders didn't draw big crowds in the A-League days, the interest was there."
Especially when the opponent was Portland.
"Yeah," Waibel says with a laugh. "The two cities love to hate each other's teams."
And so they will go at it again, Sunday night in Seattle. It will be the seventh time the Sounders and Timbers have met as MLS rivals. To this point the series stands at 2-1-3 in favor of the Sounders, and their only meeting this year, back on March 16, was a 1-1 tie.
It’s believed that the only match in the world this weekend that will draw a bigger crowd than what's expected at CenturyLink will be in Germany, where Bayern Munich host Bavarian rivals Nurnberg at the Allianz Arena, which has a capacity of 71,437.
"Even the non-soccer fans are talking about this game," says Keller. "There's an acknowledgement that what's about to happen at CenturyLink is a really big event."
And another chapter in history.