Dallas has a 5-0-2 record over its last seven outings and has not given up a goal in five games.
Seattle suffered its first loss in four contests despite outshooting Dallas 19-7.
Dallas scored on a counterattack, with Shea running onto a pass from Andrew Jacobson and putting a one-timer past Kasey Keller. It was Shea's fourth goal of the season.
Swim Week Miami Beach 2014 [PHOTOS]