BOSTON — The 76ers missed out on doing something that rarely happens.

Saturday night’s 116-95 loss to the Boston Celtics denied them from sweeping their longtime Atlantic Division rival in a season series for the first time since the 2000-01 campaign.

The Sixers (31-19), instead, concluded the teams’ four-game season series with a 3-1 advantage. A win would have also marked just the fourth time Philly recorded a season-series sweep of Boston. The other times were during the 1977-78 and 1949-50 seasons, the latter being when the team was located in Syracuse.

The Sixers have now lost three straight road games, and nine of their last 11. They’ll take a 9-17 road mark into Monday night’s game in Miami. A game in Milwaukee follows on Thursday.

Home game vs. road game disparity on three-pointers is one of the main reasons for Sixers road woes.

The Sixers are shooting 37% from three at Wells Fargo Center where they have a 22-2 record. However, they were shooting just 33.5% on threes on the road heading into Saturday’s game. And Saturday’s numbers didn’t help. The Sixers missed their first seven attempts en route to shooting 7-of-33 for 21.2%.

Boston's Gordon Hayward drives between the Sixers' Furkan Korkmaz (30), Tobias Harris (12) and Al Horford (42) during the second half.
Michael Dwyer / AP
Boston's Gordon Hayward drives between the Sixers' Furkan Korkmaz (30), Tobias Harris (12) and Al Horford (42) during the second half.

Boston’s Jaylen Brown finished with a game-high 32 points and nine rebounds. All-Star Jayson Tatum added 25. Former Roman Catholic standout Brad Wanamaker finished with a season-high 15 points in a reserve role.

Ben Simmons was one of the Sixers’ few bright spots.

The Celtics couldn’t stop the point guard, who finished with 23 points, 9 rebounds, 5 assists, and 4 turnovers. He made 9 of 14 shots from the field. He kept attacking the basket.

Meanwhile, Joel Embiid struggled from nearly everywhere except the foul line. He made all nine of his free throws en route to finishing with 11 points. The three-time All-Star starter, however, made just 1 of 11 shots from the floor, blocked 2 shots, had 5 rebounds and finished with 4 turnovers (all coming in the first quarter) while playing 23 minutes, 26 seconds. Embiid had only three rebounds through three quarters.

He refused to speak to the media following the second-worst shooting performance of his NBA career. The only one worse was when he 0-for-11 in a scoreless outing at Toronto in December.

Horford finished with 9 points, 9 rebounds and 4 assists after missing Thursday’s road loss to the Atlanta Hawks with left knee soreness. He shot 4-for-11, including 1-for-6 from three.

The game marked the first time Horford played at T.D. Garden since leaving the Celtics in June to sign a four-year, $97 million deal with the Sixers.

He was unable to play in the Philly’s win at Boston on Dec. 12 due to left knee soreness and left hamstring tightness. Back then, the Celtics honored him with a video. Fans responded with a a standing ovation. On Saturday, there was a mixed reaction when he was introduced. He was booed during the game.

Coming into the game, his focus wasn’t on getting a season-series swept. The goal was on bouncing back from Thursday’s loss and getting a win in Boston.

Horford wanted the Sixers to get on a roll with two more upcoming tough road contests.

76ers coach Brett Brown stands with Al Horford during the first half of the game.
Michael Dwyer / AP
76ers coach Brett Brown stands with Al Horford during the first half of the game.

But their play on the road continues to be an Achillies heel for a team once favored to contend for the NBA Finals.

“I don’t think our focus level is where it needs to be on the road,” Horford said. “It’s something that we, coach has been harping more recently about us keeping that throughout the game, and not having those lapses.”

The Sixers’ only lead was 2-0 on Embiid’s 5-footer 17 seconds into the game. It was Embiid’s only basket.

Boston responded like a pack of crazed dogs sensing an easy prey. They jumped out to a 22-8 lead with 5:08 left in the first quarter. The Celtics went on to take a 16-point cushion (46-30) on Wanamaker’s three-pointer with 6:30 before intermission.

Embiid left the game with 4:08 left in the half. With him out, the Sixers closed out the half on a 15-8 run to pull within eight (59-51) at intermission.

But the Celtics came out hot in the second half and built a 22-point cushion (79-57) with 3:42 left in the third quarter.

So what went wrong? he Sixers

The Sixers were without Josh Richardson for the fourth straight game with a slight hamstring strain.

Boston was without four-time All-Star Kemba Walker. It marked the first of at least two games Walker will miss with left knee soreness.