Frank de Boer's Atlanta has found form and recorded a 1-0 win over Vancouver Whitecaps at BC Place Stadium.
Josef Martinez's first-half penalty was all they needed to stretch Atlanta's winning run to five and climb into third in the Eastern Conference.
Incredibly, Atlanta has not conceded once during its five-game streak.
The Sounders jumped to second in the Western Conference after a 2-1 win at home to Orlando City.
Raul Ruidiaz tapped in a Brad Smith cross for the opener before Handwalla Bwana put away Nicolas Lodeiro's delivery in the second half.
Chris Mueller's fine 20-yard effort pulled one back for Orlando, but it was unable to find an equaliser.
Seattle moved above the LA Galaxy and is now just two points behind conference leader Los Angeles FC.
Eastern Conference leader DC United was held to a 0-0 draw by Toronto at BMO Field, while Houston Dynamo and the Portland Timbers drew 1-1.