One quarter returned a glimpse of the Boston Celtics team that recently made a push for a top-three seed in the Eastern Conference.

If they can't sustain that for more than 12 minutes, their current rough patch might continue.

The Celtics will try to avoid their longest losing streak of the season against a team notorious for extended slumps when they visit the league-worst Philadelphia 76ers on Sunday night.

Boston (39-30) is not far removed from a 17-5 stretch that put it in the East's No. 3 position and within 4 1/2 games of Atlantic Division-leading Toronto.

But Friday's 105-91 loss to the Raptors just over a week later was the Celtics' fourth straight, dropping them to sixth in the conference and 8 1/2 back in the division.

Boston's slide is one game shy of its longest since early last season, and the way it has unfolded is particularly surprising.

The Celtics were third in the league in scoring from Jan. 15-March. 9, their 111.7 average ranking behind only Golden State (116.5) and Oklahoma City (112.5). During their skid, they are averaging 99 points on 40.6 percent shooting, including 29.4 from deep.

One of the only positives was Friday's third quarter, which coach Brad Stevens said was the best his team has played in two weeks.

The Celtics cut into what was once a 19-point first-half deficit with a 33-24 advantage in the third, trimming Toronto's lead to 79-74. Still, a 30-14 flop in the first quarter and a 26-17 clunker in the fourth were far too much to avoid a fourth straight road loss.

''We have to change something up,'' Isaiah Thomas said. ''We got ourselves back into the game, so we showed signs of playing like we know how, but a good team like the Raptors you can't just play one good quarter.''

Philadelphia (9-60) might be the streak-snapping opponent. The 76ers have dropped four in a row and 17 of 18, and their only two wins since Jan. 27 have come against Brooklyn, the second-worst team in the East.

The Celtics have won seven straight games in this series as they go for their second consecutive sweep. Thomas has shot 50.9 percent while averaging 25.7 points against the 76ers in the three this season.

One more win would help Philadelphia avoid matching its own NBA-low victory total in an 82-game season, set when the 1972-73 team finished 9-73.

The 76ers have struggled mightily on the boards since rookie center Jahlil Okafor was lost for the season with a cartilage tear in his right knee. They have held a rebounding advantage in one of 10 games without him, getting edged on the glass by an average of 13.1 per game.

Philadelphia was outrebounded 63-36 in Friday's 111-97 loss to Oklahoma City, the best rebounding team in the NBA.

''We're small and we're not thick,'' coach Brett Brown said after his team fell to 6-29 at Wells Fargo Center. ''We're light right now. ... I wish it was better than that.''

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