MLS Review: DC United wins goal-fest, Impact stuns Toronto
It was a goal-fest in Washington, D.C., 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 DC 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 DC's two-goal advantage, Mullins completed his hat trick and substitute Nick DeLeon sealed the victory.
— Major League Soccer (@MLS) August 28, 2016
The rout helped sixth-placed DC improve to 32 points, four clear of Orlando City, while the Fire remains rooted to the foot of the table in the east.
Montreal recorded a 1-0 away win over high-flying Toronto, who 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, who 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, who is two points adrift but can leapfrog Toronto if it beats Orlando City on Sunday.
The Columbus Crew was 2-0 winners at home to San Jose Earthquakes, Philadelphia Union defeated Sporting Kansas City by the same scoreline, while LA Galaxy and Vancouver Whitecaps played out a goalless draw in a match which saw Steven Gerrard hobble off injured.