It’s probably a stretch to suggest the Seattle Sounders and Atlanta United have a real rivalry. The two teams have only faced off in actual competition four times since Atlanta entered the league in 2017. Yet, it would also be a little insincere to suggest there doesn’t seem to be at least the makings for a rivalry.
For one, it seems as though the teams tend to measure themselves against one another, at least off the field. Atlanta came into the league and immediately surpassed the Sounders in terms of attendance and then followed that up by winning their first MLS Cup in just their second year.