The Celtics will try to end that overall skid, as well as a lengthy one on the road, when they meet the struggling Pistons on Saturday night.
Boston (23-53) lost its seventh in a row and fell for the 12th time in 13 games with Friday's 111-102 defeat to the 76ers. Philadelphia entered on a 13-game road slide since also winning in Boston on Jan. 29, and those victories are two of the Sixers' three in their last 34 games.
The other win for Philadelphia in that span came last Saturday, 123-98 over Detroit (27-49) to end an NBA record-tying 26-game losing streak.
"They've been a hard-playing team the whole year, and I'm sure they've had their down moments, obviously, throughout their losing streak," Celtics coach Brad Stevens said. "But tonight wasn't one of them; they played well, we played not well. That's that."
Boston lost a season-high nine straight from Dec. 31-Jan. 13, and its 11-game road slide is the longest since it dropped 12 straight Jan. 7-Feb. 24, 2007. The Celtics' only wins in their past 14 away from home were against Philadelphia and Milwaukee - the two worst teams in the NBA.
They've lost their last five road matchups with the Pistons while averaging 84.2 points.
Rajon Rondo had 11 points, 16 assists and 11 rebounds Friday for Boston, his first triple-double since Jan. 25, 2013, at Atlanta in a double-overtime game in which his season ended with a torn ACL.
Rondo won't be on the court Saturday because he doesn't play in back-to-back games following his reconstructive knee surgery.
"We are all professionals. We have to do a way better job than what we are doing as far as performing for the name across our jerseys, the front and the back," Rondo said. "I try to be there as much as possible to root my guys on from the bench. We have to look deep, everyone has to look in the mirror individually and try to pull out whatever they can give for these last six games."
Detroit fell for the 20th time in 25 games with a 116-104 defeat in Brooklyn on Friday. It's allowed 112.2 points per game in losing four of five.
Andre Drummond had 23 points and 18 rebounds against the Nets, who led by 22 after three quarters.
''They shot 60 percent,'' interim coach John Loyer said. ''You're not going to win an NBA game when (your opponent) shoots 60 percent.''
The Pistons, ranked 29th in the league in 3-point shooting at 31.9 percent, took 27 shots from beyond the arc.
"That's not us," said Loyer, whose team is on the verge of being eliminated from playoff contention for the fifth straight season.
Boston won for just the second time in eight overall meetings with the Pistons on March 9, as Jeff Green led six Celtics in double figures with 27 points in a 118-111 victory. Detroit's starting frontcourt of Greg Monroe, Josh Smith and Drummond combined for 68 points and 47 rebounds.