BOSTON — It was as if Brett Brown already knew what the outcome would be.

Nine hours before Tuesday night's season opener against the Boston Celtics, the 76ers coach talked about this contest being mostly a "launching pad to the season."   He didn't downplay the hype of  a Celtics squad  that defeated the Sixers in last season's Eastern Conference semifinals.

But Brown stressed that playing at a high level in the final month of the season means more than dominating a season-opening contest.

Well, his banged-up squad showed that it definitely has room to improve in their 105-87 setback to the Celtics at TD Garden.

The defeat marked their fourth season-opening loss in five seasons. The Sixers also dropped to 9-18 against the Celtics since the 2011-12 season.

The two youthful, talented squads are seen as rivals in the  Eastern Conference, and there's even talk of them reviving those pitched battles from decades ago. They'll even be showcased in primetime on Christmas Day in Boston.

Joel Embiid put an end to all that rivalry talk following Tuesday's lopsided loss.

"This is not a rivalry," the All-Star center said. "I don't know our record against them, but it's pretty bad. They always kick our [butts]. So this is not a rivalry."

But the season opener did generate hype,  though.

Going into  Boston is always special for Brown, a Maine native who grew up a Celtics fans and played at Boston University.

"The fact that we lost to them last year in the playoffs for sure [is key]," he said. "But in general, opening night is a launching pad to a fast and furious next … six months, and life moves on." The undermanned Sixers must play better  than they did Tuesday night to live up to this season's expectations.

Ben Simmons had a solid game with 19 points, a game-high 15 rebounds, eight assists and four steals. Embiid was good on some things, finishing with 23 points, 10 rebounds and two blocked shots. However, he committed five of the Sixers' 16 turnovers. Embiid also had his shot blocked four times — three by Al Horford.

Most of the duo's teammates didn't come ready to play.

Markelle Fultz had five points on 2-for-7 shooting in 24 minutes, 20 seconds of action. Both of his baskets came in the second quarter on a 14-foot pull-up jumper and a cutting layup. Fultz only played three minutes in the second half, missing all three of his attempts during that time.

Dario Saric was hampered by foul trouble, picking up three first-half fouls and having five in 22:54.  Meanwhile, Covington had eight points on 3-for-10 shooting. He was 2 of 7 three-pointers. JJ Redick, who had 16 points, went 2-for-8 on threes and 7-for-17 overall. The Sixers made just 5 of 26 three-pointers for 19.2 percent.

Jayson Tatum had 23 points to pace the Celtics. North Philly's Marcus Morris added 16 points off the bench. Kyrie Irving had seven points on 2-for-14 shooting.

This game was ugly at the start, as both teams looked like they were still in preseason mode.

The squads combined to miss 11 of their first 13 shots.  Embiid had his shot blocked twice in a four-second stretch by Horford during the missed-basket fest. In addition to misfiring, the Sixers were careless with the ball while committing six first-quarter turnovers.

Despite that, the Sixers were able to pull into a tie with the Celtics at 21 all after one quarter. Boston went on to open up a nine-point lead in the second quarter before taking a 47-42 lead at halftime.

Fultz had five points on 2-for-6 shooting at intermission, while Covington struggled mightily.  He had two points on 1-for-5 shooting. missing all five of his three pointers.

Saric only played nine minutes in the first half due to picking up three fouls.

Covington pointed out that this was just the Sixers' first game of the season.

"We have 81 more to play," he said. "We can't get hell bent on what happened in this one. We understand that we are going to send them again and they are going to be one the teams we have to go through.

"But I like I said, this is still the first game, Guys are still getting into a rhythm."

The Sixers were without their top three offseason acquisitions — Wilson Chandler,  Mike Muscala and Zhaire Smith — and reserve guard Jerryd Bayless for the opener.

Chandler, who the Sixers acquired in a trade from the Denver Nuggets, is out with strained left hamstring. Smith was traded to the Sixers immediately after being selected 16th overall. He's sidelined with a Jones fracture in his left foot.  Meanwhile, Bayless is out with a sprained left knee. Their absences were expected.

Muscala was ruled out for the game Tuesday morning with a sprained left ankle.

The 6-foot-11 reserve center said he's taking it "day by day." However, Brown said he expects Muscala to be sidelined almost two weeks.

"I sprained my ankle about a month ago before the training camp," Muscala said. "So I was kind of dealing with a lot of swelling from that. It wasn't bothering me at all, but I kind of nicked it in the last preseason game" against the Dallas Mavericks on Oct. 8 in Shenzhen, China.

"So it's just trying to get it feeling good before the season gets under way."

The Sixers acquired Muscala this summer from the Atlanta Hawks in a three-team trade that also included the Oklahoma City Thunder.