This was a huge letdown for the 76ers.

The Phoenix Suns came into the Wells Fargo Center on Monday night as losers of two straight and three of their last five games. They are the NBA's sixth-worst team record-wise.

This was supposed to be an easy game for the improved Sixers. So we thought.

The Suns prevailed, 115-101, in front of a shocked sellout crowd of 20,564.

[Box score, play-by-play]

"I think we lost that game from the jump ball," Joel Embiid said. "I think we took them lightly. We paid for it. Next time, I guess we've got to do a better job."

This marked the second time this season that the Sixers (13-10) lost to an inferior squad they were expected to dominate. The first time came in a 109-108 setback to the Sacramento Kings on Nov. 9.  On both occasions, they looked sluggish and went through the motions.

"There's a spirit and there's a disposition and sort of just a competitive fire you have to play with in his league to try to win a basketball game against anyone," JJ Redick said. "We are playing against NBA players, really good NBA players. To win, you have to have that. We were just flat."

On this night, his squad hurt itself by missing three-pointers.  The Sixers made 7 of 30 (23.3 percent) for the game.  Robert Covington slipped back into his shooting slump. He finished with 10 points on 3-for-13 shooting, including 2 of 10 on three-pointers.

While Covington and the Sixers struggled to make threes, they were torched by Devin Booker.

The Suns shooting guard finished with a season-high 46 points to go with eight rebounds and two steals.  He scored 32 points after intermission, with 19 coming in the fourth quarter. That's when he made three of his five three-pointers.

This was his 10th game of at least 30 points this season. He has scored 33 or more points in three of his last four games.

But on this night, Booker started off missing nine of his first 10 shots. Afterward, he made 16 of 22 baskets.

"I would say a shooter's mentality – keeping the same confidence: never get too high, never get too low," Booker said of being able to overcome his rough start. "Missing shots early I feel I should make, so keep shooting them. Don't get discouraged."

The Suns (9-16) had two other double-digit scorers, T.J.Warren (25 points) and Tyler Ulis (12 points, 12 assists.)

With those three leading the way, the Sixers trailed by 17 points late in the second quarter.

However, Redick pulled them within 99-94 on a three-pointer with 4  minutes, 49 seconds remaining. But Ulis responded with a three-pointer 26 seconds later. Then Booker went on a personal 13-5 run.

Booker's three-pointer at the 3:42 mark put the Suns up, 105-94.

The fans started exiting the building after Booker drained another three-pointer to make it a 108-94 game with 2:59 remaining. Then his breakaway dunk at 2:01 put the Suns up by 16 points. Then he followed up a Covington three-pointer with one of his own. And he responded to a Dario Saric layup by making a 21-foot pull-up jumper to give the Suns a 115-99 lead with 53.1 seconds left,

Ben Simmons may not have felt well, but he looked better than most of the Sixers. The point guard finished with 20 points, eight rebounds, seven assists, and six steals.

"I woke up and didn't feel like I could play," Simmons said. He said he drank a lot of fluids and arrived at the team's practice facility at around noon for treatment. Even though Simmons didn't feel that much better, he opted to play.

"I feel like my body kind of hit a wall," Simmons of the NBA's grueling schedule.  "It all caught up with me. I've just got to start taking care of myself."

But he came out strong, scoring on his first four shots. The rookie had eight points, four rebounds and two assists in the first seven minutes.

Redick paced the Sixers with 25 points. Embiid added 22 points, 12 rebounds and four blocks, posting his seventh straight double-double and 13th of the season.

However, this was missed opportunity for a Sixers squad looking to reach the postseason.

Sixers coach Brett Brown thinks it may take a 41-41 or 42-40 record to secure a playoff spot.

"And you only have so many times that you're able to poke yourself in the eye," Brown said of letting expected victories slip away. "Tonight was one of those for us here at home. We walk out of this gym not feeling great at all about very much of what we did tonight."