Boston Celtics' Kyrie Irving passes the ball under pressure by Los Angeles Lakers' LeBron James on Saturday in Los Angeles. Photo: VCG
Marcus Smart and Marcus Morris each scored 16 points for Boston, who are gaining traction in their post All-Star break playoff push.
Gordon Hayward added 15 points as the Celtics won their third consecutive game on a four-game California road trip that concludes Monday against the Los Angeles Clippers.
The Celtics' latest matchup with their storied rivals didn't really live up to the history - the Lakers are struggling mightily and appear to have given up on any chance of making it to the NBA postseason.
Irving, who missed Wednesday's victory over the Sacramento Kings with a bruised thigh, nailed a series of clutch shots down the stretch. He also tallied seven rebounds and seven assists.
Irving and James are former teammates, winning an NBA title with the Cleveland Cavaliers in 2016.
James can only dream of similar success with his current team, which has now lost five straight.
On Saturday he finished with 30 points, 12 assists and 10 rebounds, leading a ragtag Lakers crew that was missing three starters.
Moe Wagner scored a career-high 22 points in his first start for Los Angeles and Johnathan Williams added a career-best 18 points for the Lakers, who have lost nine of 11. Rajon Rondo finished with four points.
James played just 27 minutes in the game, more than six minutes less than rookie Wagner.
Elsewhere, Minnesota franchise player Karl-Anthony Towns had 40 points and 16 rebounds before leaving late in the fourth quarter with a knee injury as the Timberwolves beat the Washington Wizards 135-130 in overtime.
Minnesota outscored the Wizards 14-9 in overtime to earn their fifth straight victory at home.
Derrick Rose scored 29 points, including a clutch basket that gave the Timberwolves a 131-127 lead with 58 seconds left.
