The visitors, meanwhile, will be looking to claim consecutive victories for the third time in the MLS this season after beating Real Salt Lake at the weekend.
Match preview
After mustering just one win in eight MLS games, Portland Timbers have experienced an upturn in fortunes in recent weeks to boost their hopes of reaching the playoffs for a fifth consecutive season.
The Timbers began their promising run of form with a 2-1 victory over Real Salt Lake, before they came from two goals down to take a point off the Seattle Sounders.
They returned to winning ways in their home meeting with Los Angeles FC, prior to Saturday's home meeting with Austin FC where goals from Felipe Mora and Evander guided Portland to a narrow 2-1 away win.
After recording consecutive MLS victories for the first time this season, Portland head into Wednesday's contest in the final playoff position in the Western Conference.
The Timbers have won their last three home games against San Jose, including July's Leagues Cup meeting, which produced a 2-0 scoreline.
San Jose will travel to Portland in a buoyant mood after they ended a four-game winless run with a narrow 2-1 win over Real Salt Lake.
Jeremy Ebobisse and Rodrigues both found the net inside the opening 15 minutes to get San Jose off to a flying start and while Real Salt Lake pulled a goal back before half time, the Earthquakes held firm to claim maximum points.
With five games to play in the regular season, San Jose are in seventh position and five points clear of those lurking just outside the playoffs.
As a result, Wednesday's visitors know a victory could go a long way to securing them a place in the postseason for the first time since 2020.
However, having won just two of their 14 MLS away games in 2023, San Jose may view a draw as a more realistic aim for the midweek trip to Portland.
Portland Timbers Major League Soccer form:
L
L
W
D
W
W
San Jose Earthquakes Major League Soccer form:
W
L
L
D
D
W
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Team News
Portland interim boss Miles Joseph is unable to call upon Aljaz Ivacic and Diego Chara due to back and abdominal injuries respectively, while Jaroslaw Niezgoda, David Ayala and Eryk Williamson are all long-term absentees.
Colombian defender Juan David Mosquera is in contention to start, which could result in Eric Miller dropping to the bench.
Having scored three times in his last five appearances, Mora will continue to lead the line for the Timbers, and he will be flanked by Dairon Asprilla and Yimmi Chara.
As for the visitors, they are expected to be without midfielder Jack Skahan and forward Benjamin Kikanovic due to muscle injuries.
While Nathan continues to recover from an anterior cruciate ligament injury, Tanner Beason is set to return to the starting lineup after serving a one-match suspension.
With 21 MLS goals between them this season, Cristian Espinoza and Ebobisse will resume their forward partnership for Wednesday's encounter.
Portland Timbers possible starting lineup:
Bingham, Mosquera, Zuparic, McGraw, Bravo; Evander, Paredes, Moreno; Asprilla, Chara, Mora
San Jose Earthquakes possible starting lineup:
Daniel; Beason, Rodrigues, Trauco; Akapo, Tsakiris, Monteiro, Yueill, Cowell; Espinoza, Ebobisse
We say: Portland Timbers 2-1 San Jose Earthquakes
Portland are currently experiencing a fine run of form, and after beating San Jose on home turf in July, we think they will draw upon that experience to claim maximum points in Wednesday's contest.
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