Seattle (1-3-2) beat Colorado for the seventh straight time and got its first win of the season. The Sounders have scored just three goals while being shut out three times.
Colorado goalkeeper Clint Irwin stopped a shot from the slot by Shalrie Joseph. The ball bonded right back to Martin, who put the ball past the outstretched hands of Irvin for his first goal with Seattle.
The ball had barely passed into the netting when Martins began a series of front cartwheels into the arms of several teammates.
Colorado (2-4-2) lost for the first time in three matches. Irwin had posted back-to-back shutouts.
The Rapids played without leading goal-scorer Deshorn Brown. The rookie forward suffered a thigh injury in Friday's practice and is expected to miss up to two weeks.
Colorado had its chances in the second half. Atiba Harris hit the crossbar in the 60th minute and Kamani Hill hit it in the 85th.
Seattle goalkeeper Michael Gspurning denied a rebound chance by Danny Mwanga after Harris' chance.