Before Minnesota United plays the first playoff game in its MLS history in two weeks, it will play another Sunday at Seattle.
Win and the Loons clinch second place in the Western Conference and a home playoff game that would set up another one if they win again.
With a tie against the Sounders, United can still finish second if L.A. Galaxy loses at Houston. Lose and it still secures a first-round home game if Real Salt Lake loses at Vancouver.
They'll finish fifth and hit the playoff road if they lose and both L.A. Galaxy and Real Salt Lake win.
"It kind of starts this weekend," United veteran defender Ike Opara said. "It's pretty much a playoff game before the playoffs. We're getting a good taste of it before the real thing."
The Sounders will open CenturyLink Field's second deck with 40,000 or more fans possible.
"If you don't want to play in big stadiums with full crowds and everything on the line, you shouldn't be playing," United coach Adrian Heath said. "You should be playing somewhere else."
Seattle now has made the playoff 11 consecutive seasons and won the 2016 MLS Cup. The first 10 were with a squad including Ozzie Alonso, who returns Sunday with United.