Starting in place of the injured Obafemi Martins, Barrett scored in the fourth and 38th minutes to help the Sounders (6-3-1) beat their Cascadia Cup rivals for the first time in six tries.
A former teammate of Whitecaps coach Carl Robinson when the two were with Toronto FC, Barrett opened the scoring after taking a pass from Clint Dempsey and moving in alone on goalkeeper David Ousted.
The Whitecaps (6-4-2) had a couple chances to get back in it — including a great finger-tip save from Seattle's Stefan Frei on Pedro Morales — immediately after the goal.
Barrett doubled the lead when Vancouver defender Kendall Waston failed to close him down on the left. The striker beat Ousted with a shot to the far post.
EARTHQUAKES 2, CREW 0
SAN JOSE, Calif. (AP) — Chris Wondolowski scored his 99th MLS goal and San Jose beat 10-man Columbus.
Wondolowski opened the scoring in the 55th minute, cutting in front Jordan Stewart's cross and heading it home. It was Wondolowski's sixth of the season and his first at the Earthquakes' new Avaya Stadium. His 100th goal will tie him with Edson Buddle for eighth place on the MLS list.
Shea Salinas added a goal for the Earthquakes (5-4-2) in the 60th minute, sending a right-footed shot past goalkeeper Steve Clark.
The Crew (4-4-2) were down a man after Mohammed Saeid was disqualified in the 33rd minute with his second yellow card.
DYNAMO 3, TIMBERS 1
HOUSTON (AP) — Will Bruin scored twice, Giles Barnes had the go-ahead score in the 75th minute, and Houston beat Portland.
Bruin opened the scoring with a header in the ninth minute and added an insurance goal on a chip shot in the 83rd to help the Dynamo (4-4-4) win back-to-back games for the first time this season.
Barnes made it 2-1 with a blast after a patient back-and-forth with Alexander Lopez in the middle of the box. It was his sixth goal of the season.
Fanendo Adi tied it at 1 for the Timbers (3-4-4) in the 48th minute, shirking a physical challenge from defender DeMarcus Beasley and finishing Diego Valeri's lead pass.
IMPACT 4, REAL SALT LAKE 1
MONTREAL (AP) — Andres Romero scored twice and Montreal beat Real Salt Lake for its first victory of the Major League Soccer season.
Laurent Ciman and Dilly Duka also scored for Montreal (1-3-2) in rainy conditions.
Devon Sandoval scored for Salt Lake (3-3-5).
With assistant Mauro Biello filling in for suspended head coach Frank Klopas, the Impact scored more than two goals in a game for the first time in 25 matches since last June.
TORONTO FC 1, REVOLUTION 1, TIE
FOXBOROUGH, Mass. (AP) — Michael Bradley scored his first goal of the season and Toronto FC came back to tie New England.
Bradley used a nice individual effort to tie the match in the 53rd minute after receiving a pass near midfield. He shielded his defender down the field, beat two more Revolution players and sent a shot inside the far post. Juan Agudelo scored in the 32nd minute for New England.
Toronto (3-5-1) held off several late chances by New England (5-2-4).
RAPIDS-SPORTING KANSAS CITY, PPD
KANSAS CITY, Kan. (AP) — A thunderstorm forced the postponement of the Colorado-Sporting Kansas City game. A makeup date has yet to be announced.