BOSTON − New York, Oklahoma City, Indiana and Memphis all won their first-round NBA playoff series with Game 6 victories on Friday, leaving only one spot up for grabs in the Conference semifinals.

The New York Knicks got the staggers and almost gave up a 26-point lead but steadied to beat the Boston Celtics 88-80, Oklahoma City Thunder booked its spot in the last eight for the third straight season by downing the Houston Rockets 103-94, the Indiana Pacers withstood a big final-quarter comeback from Atlanta and beat the Hawks 81-73, while the Memphis Grizzlies completed a comeback from a 0-2 series deficit by beating the Los Angeles Clippers 118-105.

With Miami, San Antonio and Golden State already having won through to the next stage, the last spot will be decided when Brooklyn hosts Chicago in their Game 7.
Boston cut a 75-49 deficit to four points, but Carmelo Anthony made a jumper to give New York an 81-75 lead and then sank a 3-pointer, then J.R. Smith converted a three-point play to restore the double-digit lead the Knicks had nursed most of the game.

Anthony finished with 21 points for the Knicks, who won a playoff series for the first time since the Patrick Ewing era in 2000. They will host the Pacers in today’s opening game of their Conference semifinal series.

“It’s a major step for this organization, for our fans in New York who’ve been with us for many, many years,” coach Mike Woodson said. “I’m looking at the big picture and I’m only in this for one thing and that’s to try to win an NBA title. We made a major step today, but we’ve got a long way to go.”

Jeff Green scored 21 points for the Celtics, and Iman Shumpert scored 15 of his 17 points in the second half for the Celtics, who now face another offseason of talk whether to break up the aging core that won the franchise’s record 17th NBA title in 2008 and returned to the finals two years later.

Coach Doc Rivers said he hasn’t thought about his future, or the future of his aging stars, calling Kevin Garnett “as tough a competitor as I’ve ever been around” and Paul Pierce “one of the greatest Celtics to ever play.”

“He’s done so much for this franchise,” Rivers said. “We live in a day and time where guys change teams like socks. Paul has chosen to stay here throughout his career when he could have by all rights chosen to leave.

“He wanted to get it done here. I hope he’s remembered for that. I hope he comes back.”

Oklahoma City’s Kevin Durant scored 27 points and Kevin Martin added 25 to lead the Thunder over the Houston Rockets.

The top-seeded Thunder opened the fourth quarter with a big run to take the lead and cruised to the victory.

Martin finally gave the Thunder someone to take scoring pressure off Durant for the first time since All-Star Russell Westbrook had season-ending knee surgery. He had 21 points by halftime and Westbrook’s replacement, Reggie Jackson helped out by scoring 17.

James Harden, who the Rockets said had strep throat on Thursday, led Houston with 26 points.

Indiana’s George Hill and David West each scored 21 points as the Pacers held off an Atlanta rally.

The home teams had won every game of this series until Friday. The Hawks set a franchise record worst by scoring just nine points in the second quarter on 1-of-15 shooting. The defense broke down in the third, allowing Hill and West to combine for 22 points, and the Pacers built a 65-50 lead going to the fourth.

The Hawks showed some heart, slicing it to 76-73 with 2:13 remaining, but the comeback fizzled there.

Roy Hibbert added 17 points and 11 rebounds. Lance Stephenson also had 11 rebounds.

Memphis’ Mike Conley and Zach Randolph scored 23 points apiece as the Grizzlies won their fourth straight game of the series to take it out 4-2.

The Grizzlies had never won four straight postseason games before this series, and they became only the 10th team in NBA history to win four straight after trailing 0-2. They will open the second round at Oklahoma City today.

Memphis finished with seven players in double figures. Tony Allen had a postseason-best 19 points, and Jerryd Bayless had 16.

Reserve Matt Barnes scored a career playoff-best 30 points for Los Angeles. Chris Paul had 28 points before being ejected with 2:29 left for crashing into Marc Gasol off a missed free throw, though he shook hands with several Grizzlies before going to the locker room.

Blake Griffin didn’t start because of his sprained right ankle, and he scored nine points in 13:56. Caron Butler added 14.