That spelled trouble for a Los Angles squad that has been struggling without injured stars LeBron James and Anthony Davis.
Ingram scored a season-high 36 points, Williamson had 27 points and nine rebounds, and the New Orleans Pelicans defeated the Lakers 128-111 on Tuesday night.
The 20-year-old Williamson became the first NBA player younger than 21 to score at least 20 points in 21 straight games, and he did so with his usual crowd-pleasing array of alley-oop dunks and quick, powerful drives to the hoop.
"We see it every night. You almost just get used to it," Pelicans coach Stan Van Gundy said. "I didn't even think tonight was like one of his better nights. ... He's so good now, the standard's so high on the offensive end of the floor that you start to take it for granted."
Ingram helped keep the Pelicans comfortably in front with 17 points in the third quarter, showcasing his mid-range repertoire of pull-ups, fades and turnaround jumpers - often against former Lakers teammate Kyle Kuzma.
"Going against those guys again is always fun because we kind of got drafted around the same time and we were all coming up trying to battle against each other, just trying to be better than each other," said Ingram, who has scored 30 points 10 times this season, including in his past two games.
"Of course, I'm a competitor. So, I wanted to go back to some of those old days of just us going at it in practice," Ingram continued. "I just tried to get the best of him."
Pelicans guard Josh Hart - like Ingram an ex-Laker who was part of the trade that sent Davis to Los Angeles - grabbed 15 rebounds to go with five steals.
Second-year guard Nickeil Alexander-Walker scored 18 and rookie guard Kira Lewis Jr. set a new high with 16 points in a reserve role. New Orleans center Jaxson Hayes scored 15 points in 19 minutes, hitting four times inside and making all seven of his free throws.
The Lakers, lost their third straight - all without Davis and the past two without James, who sprained his ankle early in a loss to Atlanta on Saturday that started the current skid.
"We had a stretch in the second quarter where we hit a big drop, which really hurt us in this game," Lakers coach Frank Vogel said. "We didn't play well enough defensively, particularly in that third quarter. We are going to miss guys like LeBron and Anthony on both sides of the ball, so getting us organized offensively is probably my top priority right now."
Montrezl Harrell had 18 points for the Lakers, while Kuzma and Markieff Morris each scored 16. Kuzma also grabbed 10 rebounds and had seven assists.
New Orleans opened its first double-digit lead in the second quarter and went up by 17 on Ingram's 27-foot 3-pointer, one of four he hit from deep.
Kentavious Caldwell-Pope's 3 trimmed the Pelicans' lead to 59-46 at halftime.
The Lakers never got within single digits in the second half and trailed by as many as 30.
Lakers: Have lost four of their past five on the road. ... Dennis Schroder scored 15 points and Wesley Matthews had 14. ... The Lakers went 18 of 37 from 3-point range (48.6%).
Pelicans: Starting point guard Lonzo Ball missed his second straight game with a strained right hip flexor. Alexander-Walker started in his place. ... Steven Adams had 12 points and seven rebounds. ... Australian rookie Will Magnay saw his first NBA action in the final three minutes. He attempted one shot from 3-point range and missed. ... New Orleans missed 19 of 29 from 3-point territory. ... Outrebounded the Lakers 53-34 and outscored them 62-32 in the paint.
Williamson said he's not sure how long he can sustain his 20-point streak because he's trying not to be selfish with the ball on the offensive end.
"Since I have the ball in my hands a lot and my coach and teammates trust me, I could just shoot a lot and get 20 points, but my teammates and coaches know that's not the game I want to play," Williamson said. "I want to get everybody involved and hunt for the best shot. So getting those 20 points, some nights it is going to be tougher. But nights like tonight, when there's a lot of ball movement and B.I.'s doing his thing, that really opens up the game for me."
Lakers: Host the Philadelphia 76ers on Thursday night in the first of four straight at home.
Pelicans: Host the Denver Nuggets on Friday night.
https://apnews.com/hub/NBA and https://twitter.com/AP--Sports
Zion flies out of nowhere for put-back slam
Zion Williamson cleans up Eric Bledsoe's miss and puts the shot back with an emphatic slam.