The Peruvian buried his retaken penalty kick after Eloy Room, who dived to his right to save the first, was ruled to have been off his line following Video Review. Referee Jair Marrufo pointed back to the spot and Ruidiaz went the same way, putting his attempt in off Room's fingertips.
Earlier, Zardes latched onto a sublime back-post delivery by Luis Diaz and tapped into the net to put Crew SC in front in the 33rd minute.
The Sounders thought they had the equalizer 20 minutes later when Jordan Morris received the ball at the touchline and cut inside before slipping a pass to a cutting Miguel Ibarra into the box. Ibarra finished inside the far post for what he thought was his first Sounders goal but Marrufo waved the goal off for offside following Video Review.
Before that, the Sounders' best scoring chance fell at the foot of center back Xavier Arreaga, who had time and space to unleash a shot from distance on frame. But Room dived to his left and parried it away.
Both teams had opportunities late on, with Zardes and Morris failing to capitalize. Lucas Zelarayan had one final chance at the death, but his dipping long-distance free-kick was pushed away by Stefan Frei as the final whistle blew.
- THE BIG PICTURE: There are positives to draw on for both teams. Crew SC pick up a road point at a difficult venue, while the Sounders clawed back to equalize and looked the more likely team to score a late winner.
- MOMENT OF THE MATCH: It’s all about that wild penalty kick sequence. Room looked to be the hero after denying Ruidiaz, but the celebration was short-lived when it became clear the Curacao international was off his line when the kick was taken. Then the audacity of Ruidiaz to go the same way and Room actually getting a touch. Check it out again.
- MAN OF THE MATCH: Ruidiaz gets the nod for his late equalizer and the confidence to bury his retaken PK after Room saved his first.