Cooper came on in the 86th minute and just a matter of seconds later Obafemi Martins plays a smart ball into the middle of the penalty box for Cooper to hammer home.
The Sounders made a come back for the second straight time against FCD this season.
Pareja started the game with a new look and formation as Fabian Castillo and Jair Benitez began the match on the bench with Michel and Adam Moffat staring. FCD was able to get a little more space in the midfield in a 4-4-2 look that helped lead to the game's first goal.
In the 16th minute a ball was sent in to the penalty box for Blas Perez. The FCD forward got tangled up with a Sounder defender and the result was a penalty. Michel took the ball from the spot and hammered it in the left side of the goal, away from Seattle keeper Stefan Frei for his fourth goal of the season.
The first half ended with a slew of fouls and cards for both sides with FCD committing 13 fouls.
Several times FCD keeper Raul Fernandez came up big for Dallas in this one. He made a couple big stops on Marco Pappa and Clint Dempsey in the first half.
The Sounders would tie things up in the 62nd minute with a solid finish from Lamar Neagle. The play would be set up with Obafemi Martins on the wing against Walker Zimmerman. The Nigerian forward would send a ball to the near post for Neagle to put away.
Dempsey nearly put the Sounders on top in the 68th minute. Osvaldo Alonso took a bad clearance from FCD and fired off a long-range shot that Fernandez pushed wide off the post. As the ball came out Dempsey tired to get a boot on the ball but Fernandez managed to get just enough on the ball to keep it out of the net.
FC Dallas will remain on the road this week as they travel to San Jose to battle the Earthquakes on Saturday night.