Dwight Howard did enough at the foul line to help Houston hold on Monday night.
Howard had 32 points and 10 rebounds, and the Rockets beat Boston 104-92 to send the skidding Celtics to their ninth consecutive defeat.
The Celtics hacked Howard, a poor free throw shooter, over and over again in the fourth quarter and sent him to the line 14 times. The big man made six and finished 10 of 18 in all.
"We've got confidence in Dwight to make those free throws when they start doing that, so I thought it was a real good win for us," teammate Chandler Parsons said. "But it wasn't perfect."
As they fouled Howard repeatedly, the Celtics trimmed a 19-point deficit to seven in the fourth period before going dry in the final minutes.
"I said (on TV) just now, I would probably support a change in that, that wouldn't allow that, would call it intentional or whatever you want to call it, call it like it would be called in the last 2 minutes," Boston coach Brad Stevens said. "To his credit, he made one almost - maybe every time up to the foul line."
Jeremy Lin added 16 points and nine assists for Houston. James Harden scored 16 and Parsons added 14 after missing three games with a knee injury.
Parsons is having a breakout season, averaging 17.5 points (on 51.7 percent shooting) and 5.4 rebounds. He said his knee "was really good tonight. I thought it was going to be a lot more sore."
Avery Bradley had 24 points for the Celtics, on their longest losing streak since dropping a franchise-record 18 straight games in 2007 - the season before they traded for Kevin Garnett and Ray Allen to join Paul Pierce as the Big Three.
"It's hard to go through," Stevens said. "It's unenjoyable to go through. But that doesn't mean there's no growth."
Houston outscored Boston 65-38 in the second and third quarters. Howard had 12 third-quarter points as the Rockets expanded a 52-43 halftime lead to 84-65 by the end of the period.
Jerryd Bayless scored 15 of his 17 points in the fourth quarter and Brandon Bass finished with 14 for Boston.
"(Bayless) gave us a chance, just as that whole second unit did," Stevens said. "Some of those guys haven't played that much."
But the Celtics were unable to complete the comeback and Houston held on.
"We are getting a lot of experience on that, getting a lead and then giving it up," Rockets coach Kevin McHale said. "So we are getting better at that."
Houston blew a 25-point lead against the Wizards before rallying to win Saturday.
"It seemed we played with more poise in the fourth quarter than we did against Washington," Lin said.
Bradley had 14 first-quarter points, including two 3-pointers, as the Celtics opened a 27-19 lead and held the Rockets to 29 percent shooting.
Houston's second unit made some quick inroads against Boston's reserves in the second quarter, led by forwards Omri Casspi (12 points) and Parsons. The Rockets' starters re-entered with the score tied at 35 and took off on a 17-8 run to build a 52-43 halftime lead.
Jordan Crawford had 13 points for Boston.