Kaku's goal in the 56th minute was enough for the New York Red Bulls to defeat D.C. United 1-0 on Sunday at Red Bull Arena in Harrison, N.J.
New York trails Eastern Conference leader Atlanta United by two points, while eighth-place D.C. had a three-game winning streak and a five-game unbeaten streak snapped.
Kaku, Major League Soccer's assist leader with 14, scored his fourth goal after a clearance by D.C.'s Kofi Opare landed at his feet. Kaku feigned a shot, dribbled left and shot from 22 yards.
The goal came four minutes after D.C. goalkeeper Bill Hamid covered the lower left post to save an attempt by Kaku.
D.C.'s Wayne Rooney missed a golden opportunity for the equalizer in the 66th minute, striking the ball off crossbar from 10 yards.
Red Bulls goalkeeper Luis Robles made two saves for his ninth shutout of the season and 58th of his career, including a 1-0 win at D.C. on July 25.
D.C. threw the first punch in the matchup of MLS originals. In the 10th minute, Rooney tried to sneak a free kick to the near post, but Robles pushed the shot aside.
On the ensuing corner kick, New York mounted a counterattack that got Daniel Royer open on the right side of the box, but he missed with his left foot to deny his seventh goal in the past eight games.
D.C.'s Junior Moreno forced a save by Robles in the 25th minute, and teammate Oniel Fisher could not convert a follow-up header.
Hamid was tested in the 38th minute when he made a two-handed save of Derrick Etienne Jr., who was flying down the right flank.
Both teams are home Wednesday. The Red Bulls play the Houston Dynamo; D.C. hosts the Philadelphia Union.