On Sunday, Seattle Sounders FC travel to the Portland Timber's Providence Park for the teams' fourth meeting this season.
The Rave Green have twice defeated their Cascadia rivals, including a US Open Cup elimination, and also came from two goals down to draw 4-4 on their last trip to the Rose City in April.
Though the Timbers have an inferior record in this derby, losing 45 of 87 meetings that predate Major League Soccer by almost 30 years, they are on a high after a midweek CONCACAF Champions League win, and face a stuttering Seattle side.
Despite moving back to the top of the Supporters' Shield standings with a 1-1 home draw against the San Jose Earthquakes, the Sounders have now won just two of their last seven league matches, after only one defeat in their previous dozen.
However, the first of that duo of successes came against Portland, and form will be thrown out of the window again this weekend.
While there are several heated rivalries in the MLS, the Timbers versus the Sounders tops the lot. The clubs can boast two of the most talented rosters in the United States, along with impressive stadiums and deafening crowds - and on occasions such as these, tifo and fireworks are thrown in for good measure.
Caleb Porter's side are clinging to the coat-tails of the play-off places, meaning there could yet be another pair of clashes, with a repeat of last year's Western Conference semi-final potentially thrown up.
With ESPN televising Sunday's match in both the US and the United Kingdom, we've created a Premier League-friendly guide to this Pacific Northwest face-off.
Taking key players from either side, we've found some similarities to stars currently plying their trade in England's elite division...