The closest either side came in the first half was when Kendall Waston nearly opened the scoring for Seattle with an own goal, as Joevin Jones hit a cross that the Costa Rican scrambled onto his own crossbar in the 36th minute.
With just over 15 minutes to play, Seattle center back Chad Marshall was forced to limp off in what could be a major blow to the Sounders' hopes of repeating as MLS champions.
The action never quite got going on the night, as both sides appeared content to move on to the second leg with a 0-0 draw.
The scene will now shift to CenturyLink Field in Seattle on Thursday for the second leg. Kickoff is at 10:30 p.m. ET.