BOSTON — Kyrie Irving’s shoulder wasn’t sore enough to keep him from cheering for Marcus Morris Sr. when he hit three 3-pointers to start the second half and propel Boston to a double-digit lead.

Al Horford’s injured knee didn’t keep him from leaping to his feet when Jayson Tatum drove past Anthony Davis for a dunk.

With four of their regulars relegated to cheerleaders, the Celtics got a season-high 31 points from Morris and another 21 from Tatum to beat New Orleans 113-100 on Monday night for their sixth straight victory.

“The first thing was be a leader,” Morris said. “We had a lot of guys down … and keep trying to play the right way with the guys out there.”

Anthony Davis scored 41 points and Julius Randle had 20 points and 11 rebounds for New Orleans, which was playing back-to-back games after beating the Pistons in Detroit on Sunday. But Davis also had two shots blocked by Celtics rookie Robert Williams III.

“He had 41,” Pelicans coach Alvin Gentry said. “I think everybody has gotten their shot blocked at one time or another.”

Jaylen Brown scored 19 for Boston, which was also without Gordon Hayward and Aron Baynes. Williams, in the longest appearance of his career, had career highs of seven points and 11 rebounds, while picking up three blocked shots — two on Davis.

“Well, he held him to 41,” Celtics coach Brad Stevens joked. “I thought Robert did a lot of good things. When you’re shooting jumpers and Robert’s in the vicinity, you feel him.”

The Celtics scored nine straight points in the last four minutes of the first quarter to take a lead they would never relinquish. They led 59-53 at the half before Morris hit three 3s — one from the left corner, one from the right wing and one from the top of the key — to make it 68-55.

New Orleans never got closer than nine points after that.

TIP-INS

Pelicans: Davis had been questionable with a right hip contusion, but he played 38 minutes. … Lost 124-107 in the only other meeting this season, on Nov. 26, and have now lost seven of their last 10 against Boston. … Fell to 4-11 on the road.

Celtics: Were coming off the most lopsided victory in franchise history, a 56-point win over the Chicago Bulls on Saturday. … Missed eight of their first nine 3-point attempts. After Morris hit three 3s to start the second half, they missed 11 in a row.

Williams had appeared in just nine box scores this season, never playing more than 8 minutes, 37 seconds. His previous highs were four points and three rebounds; he also matched his best with three blocked shots.

How did he feel about guarding Davis?

“I definitely watched the highlights, even when he was at Kentucky. I was a big fan,” he said. “It was a great assignment.”

Brad Wanamaker, who spent six seasons in Europe and one in the developmental league, matched his career high with four points. He had played in only eight games before Monday and topped his career highs with 18 minutes (old high 9:06), three rebounds (1), and matched his best of four assists.

Horford was nursing a sore left knee, Irving had a sore right shoulder, Hayward was ill and Baynes was out with a sprained ankle. The four players combine to average more than 50 points, 21 rebounds and 14 assists this season.

The Pelicans have alternated wins and losses over their last eight games.

“Win one, lose one, win one, lose one for the past eight,” Davis said. “So we’ve got to put a string of wins together.”

UP NEXT — Pelicans: Host Oklahoma City on Wednesday. … Celtics: Visit Washington on Wednesday.