PORTLAND, Ore. — Sebastian Blanco scored in the 86th minute and the Portland Timbers beat the Seattle Sounders 1-0 on Sunday in the 100th match between the rivals.

The rivalry dates to 1975 in the North American Soccer League. It gained national attention when the Timbers joined the Sounders in Major League Soccer in 2011.

Seattle still has a 9-6-6 advantage in league games, but the Timbers haven't lost in five straight at home against the Sounders.

Blanco's late goal helped the Timbers (4-3-2) extend their winning streak to four games.

Portland Timbers goalkeeper Jeff Attinella (1) prevents Seattle Sounders midfielder Cristian Roldan (7) from scoring in the second half at Providence Park on Sunday, May 13, 2018, in Portland, Oregon. (Photo: Jaime Valdez, USA TODAY Sports)

Both sides had chances in the first half. Diego Valeri's shot for Portland in the 39th went wide left, and Clint Dempsey's attempt in the 44th for Seattle (2-5-2) was too far right.

There were also a few notable yellow cards, the first on Seattle's Jordy Delem in the 34th minute that the crowd at Providence Park clearly thought was a red. There was another on Timbers defender Liam Ridgewell in the 44th, and Alex Roldan fouled Valeri for a yellow in the 75th.

Portland's Andy Polo had a shot in the 68th minute that was stopped by goalkeeper Stefan Frei.

Blanco broke through, charging at Frei and then perfectly placing an angled shot from just outside within the left post for his team-leading fifth goal.

When MLS granted franchises to Portland and Vancouver, the league hoped to build on the regional rivalry already in place in the Pacific Northwest. The trio already played for the Cascadia Cup, a three-way competition based on points that was created by supporters of the teams in 2004, when they were all part of the USL.

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May 13, 2018; Portland, OR, USA; Portland Timbers midfielder Sebastian Blanco (10) puts on a Chucky mask in celebration after scoring a goal in the second half against the Seattle Sounders at Providence Park. Troy Wayrynen-USA TODAY Sports
Troy Wayrynen

Sunday's match did not count toward the Cascadia Cup because this year the MLS schedule between the teams is unbalanced, so one of the games between the Timbers and the Sounders had to be thrown out.

It was possible that Portland midfielder David Guzman would return for the Sounders match, but he was not available. The 28-year-old Costa Rican sprained his knee during international duty at the end of March, and the national team has been careful about his return because he'll likely figure into the team's World Cup plans.

On Seattle's side, Roman Torres has a hamstring injury that is expected to sideline him for some four weeks and could put his chances of playing for Panama at the World Cup in jeopardy.

Also missing was Nicolas Lodeiro, who is nursing a fractured toe. Lodeiro is also a possible national team call up for Uruguay. The deadline for the 32 World Cup teams to announce preliminary rosters is Monday.

The Timbers got off to a rocky start this season under new coach Giovanni Savarese. They were winless in their first five matches, which were all played on the road because of the ongoing expansion project at Providence Park. But Portland had since won three straight, including last weekend's 1-0 victory at San Jose.

The Sounders were struggling with just one victory in seven games to start the season, falling into last place in the Western Conference. But they got a boost with a 2-1 victory against Toronto — their MLS Cup rivals — on the road Wednesday night.