HOUSTON -- Rockets coach Mike D'Antoni was quick to admit that when it became obvious that the Lakers could offer little defensive resistance against his team, the Rockets' attention to detail began to wane. But when the Lakers mustered some verve in the second half, the Rockets rediscovered their purpose.

Reserve guard Lou Williams scored 30 points against his former team and James Harden recorded his 17th triple-double as the Houston Rockets cruised to a 139-100 victory over the Los Angeles Lakers on Wednesday night at Toyota Center.

Williams, acquired at the trade deadline, hit his first seven shots and finished 11 of 17 over 32 minutes. He added four rebounds, seven assists and two steals and was a sparkplug as Houston darted to a 49-30 lead with 8:29 left in the first half.

The Rockets (47-21) won their third consecutive game. They also routed the Lakers 134-95 on Dec. 7. Houston improved to 25-1 when scoring 120-plus points.

Harden delivered an uneven performance, posting 18 points, 12 rebounds, 13 assists and nine turnovers. Houston committed only three turnovers in the first quarter but Harden eclipsed that total on his own in the second period with five in seven minutes. The Lakers (20-48) clawed to within 67-59 with 9:41 left in the third quarter but could not take full advantage of the Rockets' malaise.

"That was our problem," D'Antoni said of the wavering intensity. "You do risk a little bit because you've got to be careful (losing focus) but they finished it up OK.

"We played all right. We had a couple guys that just kind of played but that's OK."

In losing for the 11th time in 12 games, the Lakers were undone by nine first-quarter turnovers. Houston scored 13 points in transition in the period, led by as many as 14 points in the quarter and carried a 37-26 advantage into the second.

"I think that's the way that we get ourselves going," Rockets forward Trevor Ariza said of the fast-break offense. "When we turn it up on the defensive end, get a lot of easy looks, the basket starts to get bigger, shots start to go in and you start to feel a little bit better about yourself."

Forward Julius Randle was one bright spot for the Lakers, pairing a career-high 32 points on 13-of-17 shooting with eight rebounds and some assertive, flailing elbows. Rookie Brandon Ingram and Jordan Clarkson chipped in 18 points apiece.

Ariza scored 20 points on 7-of-9 shooting for the Rockets. Clint Capela recorded his 12th double-double with 15 points and 10 boards while his backup Nene had 10 points off the bench. Williams paced four Houston reserves in double figures, drilling 7 of 9 3-pointers as Houston shot 41.9 percent on 3s.

"We need to figure out as a group, not individually, but as a group how to handle adversity and how to react when things get tough," Lakers coach Luke Walton said. "We do a lot of blaming other people and we need to look at ourselves and control what we can control. Until we do, unfortunately, there are going to be a lot of frustrating nights like tonight."

Despite surrendering 32 points off 21 turnovers, the Rockets were never seriously threatened after establishing their cushion, one that came despite the Lakers shooting 52.4 percent in the opening period. Those Lakers turnovers enabled Houston to fashion a plus-7 advantage on field goal attempts with Harden dominating to the tune of 12 points and eight assists in the period.

Williams caught fire in the second, scoring 17 points on 6-of-6 shooting. He followed his three-point play at the 11:43 mark with three consecutive 3s, the final 3 upping the margin to 19. Williams shot 14 of 57 in his previous six games.

"That's what he does," Randle said of Williams. "He just scores the ball and I'm happy for him and it (stinks) that he did it against us. But good luck for him."

NOTES: Lakers coach Luke Walton re-inserted G Nick Young into the starting lineup as part of a late-season evaluation of the roster. Young played 23 scoreless minutes, missing all nine of his shots. Young, who sat the previous two games, joined G Jordan Clarkson, F Brandon Ingram, F Julius Randle and C Ivica Zubac. The Lakers also announced veterans Timofey Mozgov and Luol Deng as healthy scratches for the remainder of the season. ... The Rockets ranked 24th in the NBA in turnover rate (15 percent) prior to the All-Star Game. They were fourth since the break at 12.5 percent before committing 21 turnovers against the Lakers. ... Houston won the season series against the Lakers for a fourth consecutive season, a franchise first.