The second leg between second-seeded Real Salt Lake and third-seeded Seattle will be played Nov. 8 in Utah.
In three regular-season matches and Friday's playoff opener, the teams have managed one goal between them, scored by Fabian Espindola in RSL's 1-0 victory at Seattle on May 12.
Rimando had saves on two point-blank shots by the Sounders late in the first half.
First, he deflected a header by Sammy Ochoa onto the top of his net in the 33rd minute. Then on the ensuing corner kick, he stopped a 6-yard shot from straight in front by Seattle's Jhon Kennedy Hurtado.
Rimando played the last 19 minutes of the game with a bandage alongside his right eye after a hard collision in the box with Seattle's Christian Tiffert. Rimando was on the ground for nearly five minutes before play resumed.
Gspurning, whose 0.73 goals-against average was the best in MLS, also had two nice stops.
Early in the 24th minute, Gspurning came all the way out to the top of his penalty area and slid to knock the ball off the foot of Real Salt Lake's Nick Gravaboy. In the 85th minute, Gspurning jumped to his right to save a diving header by RSL's Paulo Junior.
Both teams were missing some of their goal-scoring prowess. Sounders forward Eddie Johnson, who had a team-record 14 goals during the regular season, did not play because of a left abductor strain that he suffered during last Sunday's regular-season finale at Los Angeles.
Espindola, Real Salt Lake's second-leading scorer with seven goals, went out at halftime with a hamstring injury.