PORTLAND, Ore. (AP) — The chase for the Pacific Northwest's Cascadia Cup continues on Sunday when the Timbers face the Sounders in an impassioned rivalry that dates back nearly 40 years.

Portland coach Caleb Porter appreciates the long-simmering duel, but his eyes are on the potential for a few much-needed points as the season winds down.

"Ten games to go," Porter said. "I need everyone's best."

Portland is clamoring to return to the MLS playoffs after advancing to the Western Conference championship last year. After the Timbers host the Sounders, they'll face the other Cascadia Cup rival, the Whitecaps, next weekend in Vancouver.

"The next two games are very, very important to us in a lot of ways," Porter said. "Two Cascadia games. And it's a chance for us to go up (in the standings)."

The defending Cascadia champion Whitecaps currently lead the three-way rivalry that is based on points. The Timbers lag in last, and a loss Sunday would effectively eliminate them.

"I think I can speak for everyone, we're raring to go on Sunday," Portland defender Liam Ridgewell said

The rivalry between the three teams goes back to 1975 when the trio played in the North Americana Soccer League.

The Cascadia Cup — at least the trophy itself — was introduced in 2004 when the teams were part of the United Soccer Leagues First Division. Supporters pooled their money to buy a 2-foot tall silver cup that lists the years each team has won.

Sunday's match will be the 88th meeting between the Timbers and the Sounders. The last league match was in Seattle on July 13, with the Sounders coming out on top 2-0. Clint Dempsey returned from World Cup duty to score in the 71st minute.

Dempsey had a hat trick in a 4-all draw at Portland's Providence Park to kick off Cascadia Cup play in April.

The Timbers (7-7-10) are coming off a 4-1 win over Alpha United FC Wednesday in Guyana to open CONCACAF Champions League play. The Timbers took a squad consisting mainly of reserves, while the starters stayed home.

Portland's last league game was a 1-1 draw at New England last Saturday. Ridgewell scored his first career MLS goal in the second half.

The match in Portland caps a rocky stretch of five matches in 15 days for the Sounders. Their last was a 1-all draw at home with the San Jose Earthquakes on Wednesday. Dempsey and Brad Evans played only limited minutes, and Seattle coach Sigi Schmid gave most of his starters a day off on Friday to make sure they were fresh for Sunday's match.

Sounders defender DeAndre Yedlin summed up his team's feelings about the trip south: "Winning this game could put this bad stretch to rest."

Seattle (13-7-3) sits atop the league's Western Conference. Portland rests in sixth place — behind the fifth-place Whitecaps — as the teams all make their season-ending push toward the playoffs.

The Sounders have gone 1-3-1 in their last five MLS matches, while the Timbers have gone 3-1-1 in theirs.

"It's funny, that red line (between who is in and who is out), it's like gravitational pull," Porter said. "Teams that are up tend to go down and teams that are down tend to go up."