Patrick Mullins scored a hat trick as D.C. United crushed the lowly Chicago Fire 6-2, while the Montreal Impact earned bragging rights over rival and Eastern Conference leader Toronto FC in MLS on Saturday.
It was a goal-fest in Washington, with playoff chasing United finishing strongly to extend its unbeaten streak to six matches.
Luciano Acosta opened the scoring in the 25th minute but the Fire equalized six minutes later via Michael de Leeuw. After Chicago's Khaly Thiam saw red in the 34th minute, a quick-fire brace from Mullins had United 3-1 up with the interval fast approaching until Razvan Cocis pulled a goal back on the stroke of halftime.
And it was one-way traffic in the second half as Patrick Nyarko restored Uniteds two-goal advantage, Mullins completed his hat trick and substitute Nick DeLeon sealed the victory.
The rout helped sixth-place D.C. improve to 32 points, four clear of Orlando City, though it has played a game more, while the Fire remain rooted to the foot of the table in the east.
Montreal recorded a 1-0 away win over high-flying Toronto, which was left licking its wounds.
Ignacio Piatti settled the "401 Derby" with 17 minutes remaining as the Impact snapped a 12-game winless streak in Toronto, despite Calum Mallace's red card and Didier Drogba's hamstring injury in a fiery clash.
Toronto, which was limited to just three shots on target throughout, lost reigning MVP Sebastian Giovinco to a leg injury midway through the second half.
The loss opens the door for New York City FC, which is two points adrift but can leapfrog Toronto if it beats Orlando City on Sunday.
Western Conference leader FC Dallas scored three unanswered goals in the second half to account for the Houston Dynamo 3-1.
The Columbus Crew were 2-0 winners at home over the San Jose Earthquakes, the Philadelphia Union defeated Sporting Kansas City by the same scoreline, while the LA Galaxy and the Vancouver Whitecaps played out a goalless draw in a match that saw Steven Gerrard hobble off injured.