The Cleveland Cavaliers' woes continued after going down to the Chicago Bulls, while the Houston Rockets lost to the Portland Trail Blazers.
Reigning NBA champions the Cavs were dealt a third consecutive defeat, beaten 99-93 by the Bulls on Thursday.
The Bulls overcame an 11-point third-quarter deficit to rally past the Cavaliers, who dropped half a game behind the Boston Celtics for the Eastern Conference lead.
Houston suffered back-to-back defeats after losing 117-107 to the Trail Blazers.
MVP contender James Harden scored 30 points in Houston's defeat on the road in Portland.
BULLS COMPLETE SEASON SWEEP AS LEBRON MOVES PAST SHAQ
With their win, the Bulls swept the Cavs 4-0 in the season for the first time since 2011-12.
The Bulls (36-39) had a game-high 28 points from Nikola Mirotic and another 25 points from Jimmy Butler to keep their playoff hopes alive. Chicago moved within a game and a half of the Miami Heat and the Indiana Pacers for the final spot in the Eastern Conference.
Cleveland have lost five of their last seven and even 26 points from LeBron James could not stop the skid.
James moved past Shaquille O'Neal for seventh place on the NBA's all-time scoring list, but 19 of his 26 points came in the first half as the Cavs held a 50-41 lead at the break.
TRAIL BLAZERS SILENCE HARDEN AND ROCKETS
Damian Lillard and Jusuf Nurkic starred for the Trail Blazers.
Lillard (31 points, 11 assists) and Nurkic (19 points, 11 rebounds) had double-doubles to hand the Rockets another loss.
CLIPPERS, PISTONS WIN
Blake Griffin and Chris Paul starred as the Los Angeles Clippers won 124-118 - handing the Phoenix Suns a 10th consecutive loss.
The Detroit Pistons edged the Brooklyn Nets 90-89 and the Minnesota Timberwolves trumped the Los Angeles Lakers 119-104.
10 IN A ROW FOR WARRIORS?
The in-form Golden State Warriors can extend their winning streak when they host the Rockets on Friday. The San Antonio Spurs are away to the Oklahoma City Thunder, while the slumping Cavs entertain the Philadelphia 76ers.