The Wells Fargo Center crowd rose to its feet with about a minute remaining, trying to will James Harden to the basket with the 76ers trailing by three points. The All-Star point guard slid past his defender, but his layup attempt rolled off the rim.

That was not the Sixers’ final opportunity to close the gap, or close out a win against the Toronto Raptors. But it epitomized a Sunday night when their fast start abruptly fizzled into a 93-88 defeat in the first game of a key late-season back-to-back set.

“I didn’t think we had the right approach,” coach Doc Rivers said. “Don’t know why, but we didn’t tonight. Everyone just stood around and watched each other play. That’s not how we’ve been playing. It’s funny, you feel like you’re getting it and then you have one of these.

“You don’t overdo it, but we did not play with any urgency tonight at all.”

Up next for the Sixers: the Eastern Conference-leading Miami Heat, for a game that tips off 23 hours after Sunday’s start and is a prime date the Sixers (43-27) could need to rest stars such as Harden and Joel Embiid. Though Harden said he plans on playing against the Heat, Embiid did not speak to the media because he was seeing the team dentist after getting popped in the mouth during the game.

The Raptors won without All-Star point guard Fred VanVleet (rest) and starting wing OG Anunoby (finger) against a Sixers team they could meet in the playoffs. This would have been the matchup if the postseason began Sunday, and the Raptors won their first play-in game. But by the end of the night, the Sixers had fallen into a tie with the Boston Celtics (44-28) for third place in a stacked Eastern Conference. The Sixers and Raptors will play for the final time of the regular season April 7 in Toronto.

A Pascal Siakam turnaround jumper gave the Raptors an 89-86 lead with 2 minutes, 7 seconds to play. After Harden’s miss at the rim and an Embiid turnover on the Sixers’ next possession, the Raptors kept the Sixers in the game by missing three free throws in a span of less than nine seconds and allowing Tyrese Maxey to drive for an uncontested dunk to cut the advantage to 90-88. But Harden was called for an offensive flagrant foul on a drive with 2.7 seconds to play, and Chris Boucher and Siakam finished the game off at the line.

“I thought it was an offensive foul,” Rivers said. “They sold out and came and tried to get the ball out of [Harden’s] hands, so give them credit. It’s a tough one, because you’ve got to go up with it.”

Toronto coach Nick Nurse said before the game that his defense had “a lot of things on the menu” to throw at All-Stars Embiid and Harden. It largely worked, as those two and Tobias Harris combined to shoot 13-of-41 from the floor. Harden also missed two free throws with less than three minutes to play that would have given the Sixers a one-point lead.

“I’ve just got to be better,” Harden said of his late miscues. “That’s it. It’s pretty simple. And I will be. There’s no thought into it. Be better. Move on. Next game.”

» READ MORE: Doc Rivers addresses why Sixers’ bench isn’t scoring as much

Instead, the Sixers got lifts from Maxey (19 points, 4 assists) and Matisse Thybulle (12 points on 4-of-6 shooting) while that trio struggled. Siakam led the Raptors with 26 points.

Great first, bad second

The Sixers scored 37 first-quarter points and led by as many as 16, when Embiid found Maxey for a fast-break dunk to quickly make the score 28-12. They made 11 of their first 16 field goals and shot 60% in the period. They did not commit a turnover. They got nine points from Maxey and eight from Thybulle.

The Sixers then scored only 51 points the rest of the way: 17 in the second quarter, 20 in the third and 14 in the fourth. The lack of pace and execution “even out of timeouts” failed Rivers’ team on a night when it held the Raptors to 37.6% shooting from the floor.

“When you don’t move the ball, you’re not gonna get good shots,” Rivers said. “... It happens. The sun’s coming up tomorrow and we’ll be fine, but it’s just no fun to watch when it does happen.”

The Raptors gained their initial momentum momentum with 11-2 burst during the second quarter’s final three minutes. Toronto got within 52-49 on a Precious Achiuwa three-pointer, cut that deficit to one on a Siakam dunk with about a minute to play, and seized a 57-54 lead on two Gary Trent free throws and a tip-in through contact by Scottie Barnes in the last minute.

Embiid’s uneven night

Embiid played against the Raptors after being listed as questionable for the third consecutive game with back soreness. His results were uneven by his lofty standards: 21 points on 6-of-20 shooting and 13 rebounds. The lack of overall offensive flow meant Embiid did not get his typical deep post touches, Rivers said.

“We didn’t get down there much, and so that’s on us,” Rivers said. “That’s on Joel, too. We’ve got to post up more. We’ve got to call more to get him down there, and then we’ve got to execute it when he’s down there.

“We came out of the one timeout and we had Joel deep [and] we threw the ball away. That kind of stuff can’t happen.”

Embiid went 4-of-16 through three quarters, but began to draw fouls during a stretch late in the period. He made three consecutive trips to the free-throw line, helping the Sixers rebuild a 70-63 advantage.

Shortly after reentering in the fourth, he somehow punched the ball into the basket through contact and hit the ensuing free throw to tie the score at 82 with less than eight minutes left and then finished inside to reduce Toronto’s lead to 85-84. But he air-balled a contested jumper with his team still trailing by that margin with less than three minutes to play, and misfired on a turnaround attempt with the Sixers down 89-86.

The MVP contender missed eight of his 12 attempts from the floor and shot only two free throws in the first half, although he did convert an acrobatic finish late in the second that marked the Sixers’ only field goal in the final three minutes.

Halfway with Harden

Harden began playing with the Sixers after the All-Star break, with 24 regular-season games remaining. The Sixers crossed Game 12 with Sunday’s loss and are now 8-3 when Harden is in the lineup. He finished Sunday with 17 points on 5-of-12 shooting with 9 rebounds, 8 assists and 6 turnovers.

Rivers reiterated before the game that he believes his team is “trending in the right direction,” but still had weaknesses to improve during the season’s final three weeks. The coach acknowledged that Sunday was a step back, and some of those weaknesses showed up.

A 56-40 rebounding edge for the Raptors, which led to 18 second-chance points, was the most glaring. Though their length and athleticism make them difficult to match, Rivers was also upset with the Sixers’ lack of execution in that area.

“We talked about it all day, about you have to go block them out first and then turn,” Rivers said. “Instead, we turned to go. They’re bigger. They’re longer. So if you just turn, they’re just gonna jump over your back and keep the ball alive. That’s what they did

“We just got our butt kicked. That’s all I have.”