The Sounders got two goals and a red card from their star forward and made life tough on themselves before Lamar Neagle put the match to bed.
Martins opened the scoring just after the half-hour mark, collecting a cross from Brad Evans and tucking it home.
The Nigerian was on point again minutes later from the penalty spot. A two-footed tackle from Jhon Kennedy Hurtado in the box was judged to be a penalty and a second card of the night for the big defender, who was sent off before Martins put the penalty away.
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Despite being two goals and one man down, Chicago got back into the match right away. Harrison Shipp's run into the box was not walled off well by Chad Marshall and the rookie cut back onto his left foot, opening up just enough space to finish and cut the lead in half.
After the goal Martins was sent off as part of a scuffle at midfield, though exactly what he did to pick up the straight red was not immediately clear.
A 78th-minute strike from Lamar Neagle, bent into the back post after he was allowed plenty of time to take it down in the Fire box, seemed to put the game on ice for Seattle, but Chicago would not go out without a fight.
Shipp made sure the finish would not be an easy one for the Sounders with his second goal of the night in the 82nd, a blast with his right foot from a tough angle.
The win sends the Sounders to 32 points from 15 matches heading into the World Cup break.