The Seattle Sounders have a great opportunity to secure the No. 2 seed in the Western Conference if they take care of business the next two games.
FC Dallas will miss the postseason for the first time since 2009 unless it receives some help.
Forward Eddie Johnson is expect to be in the lineup Sunday night when Seattle finishes its home schedule against a Dallas club that could be out of the playoff mix before the match ends.
With Michael Gspurning making several key saves, the short-handed Sounders (14-7-11) hung on for a scoreless draw Wednesday versus Real Salt Lake. Seattle remained three points back of RSL for the second spot, but coach Sigi Schmid's club has one game in hand as well as a slight edge in the first tiebreaker with two more goals scored.
Schmid won't be on the Sounders' touchline until the season finale Oct. 28 at Los Angeles after the league fined and suspended him one match for criticizing referee Ricardo Salazar on Wednesday.
Seattle played the final 60 minutes versus Real Salt Lake with 10 men after defender Zach Scott was issued his second yellow card.
Assistant coach Brian Schmetzer will take over Sunday with Johnson expected back into the lineup. The star forward, the team leader with 14 goals, missed Wednesday's match after two standout performances to help the U.S. advance in World Cup qualifying. Johnson scored both goals in a 2-1 win at Antigua and Barbuda on Oct. 12, then set up a score in Tuesday's 3-1 victory over Guatemala.
"We've got a game on Sunday and I'm looking forward to it," said Johnson, who didn't play in a 1-all draw at Dallas on Sept. 2 as Seattle was coming off a CONCACAF Champions League victory over Caledonia AIA in Trinidad and Tobago.
FC Dallas (9-12-11) arrives in Seattle on the brink of playoff elimination. With two games left, the club is four points back of fifth-place Vancouver, which can clinch the final spot earlier Sunday with a win over Portland.
That would also give Seattle the Cascadia Cup for the second consecutive season.
Dallas will also be eliminated if Vancouver records a draw and Seattle wins or draws.
"Even if we get the help from Portland, we've still got to get the job done," coach Schellas Hyndman told Dallas' official website. "That's what I've always been focused on was to get a good performance in your games and at the end of the season you hope you get enough good performances that you can reach your goals."
Scoring goals against Seattle could be a challenge as Gspurning has recorded three consecutive clean sheets. He made four saves in the September draw.
The Sounders will be without Scott due to suspension, but Swedish defender Adam Johansson returns from international duty and Jhon Kennedy Hurtado could see action after suffering a facial fracture in a 3-0 win over Portland on Oct. 7.
FC Dallas is 1-1-1 all-time in Seattle, winning the most recent match there last year.