Wayne Rooney was shown a red card for the second time in his MLS career as DC United lost 2-1 to the New York Red Bulls.
The Derby-bound striker was sent off in the 24th minute following a video review, after clashing with Cristian Casseres at a corner.
The visitors were also reduced to 10 men in first-half stoppage time after Amro Tarek was given his second yellow card.
Kaku opened the scoring for the Red Bulls in the sixth minute and although Ola Kamara equalised 10 minutes into the second half, Daniel Royer won it four minutes later with a penalty.
Valentin Castellanos fired his 10th goal of the season to lead New York City to a 1-0 victory over Columbus Crew.
The Argentinian scored in the 36th minute after collecting a chip from Maxi Moralez.
The Crew created some chances to pull back in the second half but an equaliser proved elusive, putting an end to the side's six-game unbeaten streak.
Victory for NYCFC moved them to within one point of Atlanta and Philadelphia at the top of the Eastern Conference.
Meanwhile, LAFC thrashed the San Jose Earthquakes 4-0 to extend their winning streak to five games.
Former Arsenal star Carlos Vela scored two while Diego Rossi and Josh Perez also found the back of the net.