A quick-fire double from Fanendo Adi saw Portland Timbers defeat archrivals Seattle Sounders 4-1 on Sunday, while New York Red Bulls also won a derby.
On the final day of MLS's 'Rivalry Week' the Timbers and Red Bulls both claimed derby victories, with the latter maintaining their perfect record against local rivals and expansion club New York City.
In Portland, the Timbers opened the scoring in the 12th minute after Diego Valeri finished off a sharp passing move with a one-touch delivery to Darlington Nagbe and the midfielder sent a rocket of a shot into the top corner.
The Sounders entered the Cascadia Cup derby without key strikers Clint Dempsey, Obafemi Martins and Chad Barrett for a variety of reasons.
But the visitors managed to equalise before half-time thanks to forward Lamar Neagle, who produced a close-range volley from Tyrone Mears' 38th-minute free-kick.
Adi blew the game open in the space of three second-half minutes, however, finishing into the top corner from Nagbe's cut-back in the 74th minute and then blasting past Stefan Frei soon after.
Rodney Wallace completed Portland's dominant performance with a goal in second-half stoppage time.
The victory took the Timbers to third in the Western Conference with 28 points, ahead of the Los Angeles Galaxy on games won, and just one point adrift of Seattle.
At Yankee Stadium, the Red Bulls made it two wins from two games against their younger brothers, with a powerful second-half display setting up their 3-1 triumph.
After Thomas McNamara struck early for City, the Red Bulls equalised a minute into the second half thanks to Bradley Wright-Phillips' impressive volley.
Chris Duvall smashed the visitors into the lead in the 52nd minute, while Matt Miazga's header with 17 minutes remaining capped off the Red Bulls' win.
