Neither Seattle nor Atlanta could find a winner in Friday's 0-0 draw at CenturyLink Field, despite United States international Clint Dempsey hitting the crossbar for the Sounders in the second half.
The Sounders welcomed MLS' newest franchise to Seattle having scored six goals and conceded five in their opening three matches.
However, Seattle and Atlanta both fired blanks for the first time this season.
It was the same result at BMO Field as host Toronto and Sporting KC failed to score.
The stalemate ensured Toronto and Sporting remain unbeaten through four games.