Both sides of the Sounders-Timbers rivalry have referred to Portland as being the “little brother” within the past month — volunteered it, even.

Seattle’s part-owner and general manager Adrian Hanauer mentioned as much in a Q&A with The Vancouver Sun when asked about the Northwest cities vying for the title of “Soccer City USA.”

“If you’re talking about numbers and competitive success and a little more history, it seems to me that Seattle is ‘Soccer City USA,’ ” Hanauer told the Sun on Oct. 8. “But little brother is excelling, as well, and we need to stay on our toes and make sure we don’t slip up, or they may catch us.”

Timbers coach Caleb Porter offered his reference after beating the Sounders, 1-0, at home Oct. 13. He was speaking of a mindset change he hoped to instill in his first year in charge.

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“There is no reason why we should be the little brother,” Porter said. “We should be a legitimate contender. We should be capable of beating the Sounders, and it not being a miracle.”

Both quotes ring true weeks later.

And if the dynamic of the country’s deepest MLS rivalry is going to change, it will happen Thursday in the second leg of a two-game Western Conference semifinal series.

If the Timbers are finally going to shed the “little brother” label, they have to preserve a 2-1 aggregate lead and triumph over Seattle when the stakes have never been higher in 38 contentious years dating to the old North American Soccer League.

The Sounders have their own demons to conquer, as well, having made it to the conference semifinals in each of its five seasons in MLS, but so far having advanced just once.

Thursday is a game to keep the season alive, but it’s also a game for legacy.

“Anytime you have an opportunity to be remembered,” said Sounders forward Eddie Johnson, “you don’t want to take it for granted.”

In the aftermath of Saturday’s opener, Portland’s first competitive win in Seattle since 2005 in the United Soccer Leagues, both teams have stressed the confidence they have going into the second leg.

The Timbers are lifted by their remarkable record at Jeld-Wen Field, having gone 11-0-4 since the season’s only home loss in March.

The Sounders draw their faith from a history of strong second-leg performances, even if they’ve had to overcome rough first legs. Seattle has won three straight when closing out a two-game series, even if two of those wins still resulted in playoff elimination.

Overall, seven teams in MLS history have lost the first leg of a two-game series at home by a single goal, and three have come back on the road to advance.

Not the worst odds, but the margin for error is as slim as it gets. Any slip-up by the Sounders and everything might change, because little brother is catching up quickly.

Note

• Schmid indicated defenders DeAndre Yedlin (sprained ankle) and Zach Scott (cracked rib) should be good to go Thursday. Forward Obafemi Martins (groin) traveled with the team and upped his training, which Schmid called “a good sign” regarding his availability.

Seattle vs. Portland
This Seattle vs. Portland rivalry has been going on a long time, and not just on the soccer pitch.
Category Seattle Portland Winner
Matt Dillon movie “Singles” “Drugstore Cowboy” Seattle. Citizen Dick rocks!
TV show “Frasier” “Portlandia” Portland, in an upset (sorry Niles).
World’s Fair 1962, Century 21 Exposition 1905, Lewis & Clark Exposition Seattle. It was all groovy, space agey.
Business behemoth Microsoft (among many others) Nike Seattle’s rich guys richer than theirs’.
College football team Washington Huskies Portland State Vikings Seattle. Scoreboard, baby (2012: 52-13)
NBA titles 1, 1979. MVP, Dennis Johnson 1, 1977. MVP, Bill Walton Tie. Portland has better shot in ’14.
Summer hootenanny Seafair Rose Festival Portland. Seafair, too loud, too loud.
Stanley Cup hockey 1917: Metropolitans win 1916: Rosebuds lose in finals Seattle. Rosebuds first, but lost. Losers.
“Louie Louie” cred Wailers’ 1961 version a hit here The Kingsmen did it best, 1963 Portland. Wailers were Tacoma, after all.
Beer Great microbrews, suds tradition Travel and Leisure: No. 1 in U.S. Portland, hic. Final score, Seattle 5-4-1.

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