BOSTON — The division title has already been clinched, and with it a spot in the playoffs. All the Boston Celtics need now is to start playing well.

Luis Scola had 27 points and 11 rebounds, making back-to-back baskets in the last 81 seconds, and the Houston Rockets scored the last 10 points of overtime Friday night to beat Boston 119-114 and send the Celtics to their third consecutive home loss.

“Probably our best win of the year,” said Rockets coach Rick Adelman, whose team has already been eliminated from playoff contention. “I couldn’t be more proud of the guys who played. … They got down. (It) looked like they had us, and we came right back at ’em, quickly.”

Aaron Brooks scored 30 with nine assists for Houston, hitting a game-tying 3-pointer with 9 seconds left in regulation as the Rockets took advantage of Boston’s missed free throws — 13 in all, and three in the last 48 seconds of the fourth quarter — to make it to overtime.

“We have been a pretty smart team,” Celtics coach Doc Rivers said. “That’s what bothered me, how many things we did out of character.”

Chase Budinger added 24 points for the Rockets, who were without Trevor Ariza because of flulike symptoms.

“This is big for the young guys coming in here,” said Kyle Lowry, who scored 18 points as a reserve. “It feels good when we just say, ‘Wow. We beat the Celtics in Boston.’ It’s a feel-good win.”

Paul Pierce scored 27 points and Rajon Rondo 23 for Boston. Rondo added 10 assists to surpass Hall of Famer Bob Cousy for the Celtics’ single-season franchise record. Rondo, who also had five steals and five rebounds, has 724 assists for the season, topping Cousy’s total of 715 in 1959-60.

Pierce missed four free throws, and the Celtics shot just 65 percent from the line. On defense, Boston allowed the Rockets to shoot 51 percent from the floor and make 12-of-18 3-pointers.

But Rivers said he was more troubled by the senseless fouls when the Celtics had a comfortable lead, and by the missed assignments that should be second-nature to a veteran team that won the NBA title two seasons ago.

“There are so many things I could point out, but I won’t,” he said. “We played like a high school team at times, as far as the way our thought process was.”

Boston scored 11 consecutive points in the fourth quarter to turn a 91-87 deficit into a seven-point lead. But the Rockets came back, finally tying it with 1:15 left on Lowry’s falling-down drive that made it 104-all.

Kevin Garnett hit a pair of free throws with 60 seconds left to give Boston a 106-104 lead, and the Rockets resorted to fouling to keep it close. The Celtics missed went 3 for 6 from the line in the last 48 seconds, allowing Houston to tie it on Brooks’ 3-pointer.

“One thing we all know is basketball is a game of runs,” said Budinger, who matched a career high in points he set just two games ago. “That’s what happened tonight. They made a run late in the fourth. Lucky enough they missed some free throws and Aaron hit a big shot for us.”

Pierce dribbled down to the final second for Boston before putting up an off-balance jumper at the regulation buzzer.

In overtime, the Celtics opened a 114-109 lead when Rondo scored on a fast break with 3:20 left.

But they did not score again.

Budinger pick up a loose ball and hit a 3-pointer to make it a one-point game with 2 minutes left. After Tony Allen’s miss, Scola scored on a putback to give the Rockets the lead. Scola added a long 2-pointer with 52 seconds left to make it 117-114 and, after Kendrick Perkins was called for a moving pick, Brooks made a pair of free throws to clinch it.

Rondo picked up a pair of assists early in the first, the second to set up Garnett with 8:45 left in the quarter and surpass Cousy. At the next break, the milestone was noted over the public address system, and the fans and Rondo’s teammates applauded.

Cousy retired in 1970 as the NBA’s career leader with 6,955. He is 14th now.

The Celtics led by 11 points midway through the first quarter, but the Rockets scored 16 of the next 19 points — and 10 in a row — to turn a double-digit deficit into a 29-27 lead with 60 seconds left. Houston led by as many as seven points in the second and took a 57-53 halftime lead when Budinger hit a 3-pointer with 4 seconds left.

NOTES: Ray Allen scored five points and played just 16 minutes because of foul trouble. … The 119 points was the most allowed by the Celtics this season. … Boston had been 3-0 in overtime this season. Houston improved to 4-3.