The Portland Timbers began their first week of playoff preparation without an opponent.

As the top seed in the Western Conference, they first had to wait for Wednesday’s winner of the knockout round between Sounders FC and Colorado. Well, at least that would have been the conventional way to go.

“To be honest with you,” said Timbers coach Caleb Porter, “we prepared for Seattle, because we knew they would most likely win. We expected this result. Our guys are up for it and ready for it and excited about it.”

So is everyone across MLS.

This was the matchup nearly everyone outside of Colorado hoped would happen in the Western Conference semifinals. It’s a dream pairing that features the fiercest rivalry in American soccer and two of the most compelling teams in the league this season.

The teams have met in postseason four times dating to 1975 in the old North American Soccer League, and this latest chapter, with perhaps the most at stake in the clubs’ 38-year history, provides the stage to take the level of contention even further — if that’s even possible.

“The rivalry is massive,” said Seattle assistant coach Brian Schmetzer, who played and coached for the Sounders over multiple decades and leagues. “Now that it’s actually a playoff series, it grows into Mount Rainer. It’s more than massive. It’s huge.”

Porter added that the series has “epic” possibilities: “I think it’s going to be one that people are talking about for a long time.”

Both sides agree: the matchup is good for everyone — coaches, players, fans and, most of all, the league.

So can this be something that moves the needle among casual and non-soccer fans? Can the skill on the field and passion in the stands help grow the MLS footprint in a crowded sporting landscape?

The big-picture gains will garner some of the attention of Sounders general manager Adrian Hanauer.

“For sure in the soccer world, this is a big matchup, a big rivalry,” he said. “Sometimes I wonder if you’re in New York City or Boston, if you barely know where Seattle and Portland are. We’ll see how reflective it is in terms of ratings and how much attention it gets nationally.”

Amid the growing buzz for the series are two exciting teams hoping to take one step closer to MLS Cup.

The Timbers have been perhaps the surprise of the season, making an astronomical leap from last season under their first-year coach. They earned 23 more points in the standings to finish first in the West and earn their first playoff berth. They improved 43 goals in goal differential, the biggest performance turnaround in MLS history.

Portland boasts the favorite for Coach of the Year (Porter) and Newcomer of the Year (midfield maestro Diego Valeri, who had 10 goals and 13 assists in the regular season). Overall, four Timbers finished with nine or more goals and five had at least seven — both best in the league.

Beating the Sounders would also give Portland as many MLS playoff series wins as Seattle.

The Sounders, with renewed confidence after beating the Rapids on Wednesday, aren’t quite ready to embrace an underdog role, however.

“They’ve got some threats,” said goalkeeper Marcus Hahnemann of the Timbers. “I think we can match them no problem.”

Note

• Sounders FC’s DeAndre Yedlin (ankle) and Obafemi Martins (forward) were being evaluated Thursday and no update was made available on their prospective availability in Saturday’s first leg.

Rooted history
A Sounders-Timbers matchup in the Western Conference semifinals is actually the fourth postseason meeting between the clubs in a 38-year rivalry.
Date League Round Winner
Aug. 12, 1975 NASL Quarterfinals Timbers, 2-1
Sept. 1-5, 2004 A-League Conference semifinals Sounders, 3-2
Sept. 16-18, 2005 USL First Division First round Sounders, 3-0
Nov. 2-7, 2013 MLS Conference semifinals TBD

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

On Twitter @joshuamayers