The top-seeded Boston Celtics and Oklahoma City Thunder rolled to convincing victories in their opening NBA playoff series on Tuesday.

Eastern Conference top seeds Boston laid down a marker with a 120-95 rout of the fourth-seeded Cleveland Cavaliers at the TD Garden.

Oklahoma City meanwhile were made to work harder by Luka Doncic and the Dallas Mavericks before finally pulling clear to seal a 117-95 victory in their Western Conference semifinal series opener.

In Boston, Jaylen Brown scored 32 points while Derrick White added 25, including seven three-pointers, in an emphatic win for the Celtics, who are chasing a record 18th NBA championship.

Boston were in complete control for most of the game, holding a double-digit lead through the second half to close out an emphatic win at the TD Garden.

Boston star Jayson Tatum added 18 points but had an off-night shooting-wise, making just 7-of-19 from the field.

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Donovan Mitchell led the scoring for Cleveland with 33 points, with Evan Mobley adding 17 and Darius Garland 14.

Brown said the Celtics’ defense had laid the foundation for the win.

“It starts with defense, we wanted to set the tone on defense and we kept them under 100 (points),” Brown told TNT television.

“But we feel like we’ve got an answer for everything so we just play the game the right way, and see what they want to take away and then we play after that.”

Boston got off to a flying start, jumping out to an early 12-2 first quarter lead before a Cleveland rally saw them edge into a 23-21 lead after Mitchell’s running three-pointer.

But Boston responded swiftly, reclaiming the lead immediately and never allowing Cleveland to get their noses in front thereafter.

After taking a 10-point lead into half-time, Boston kept the pressure up in the second half, stretching out to a 26-point lead in the fourth quarter as they romped to a comfortable win. Game two in the series takes place in Boston on Thursday.

Thunder roll past Mavs

In Oklahoma City, the Thunder and the Mavericks fought a nip-and-tuck duel before the No.1 seeds pulled away decisively in the fourth quarter.

Trailing by nine points at half-time, Dallas rallied in the third quarter to get within one point at 66-65.

But the youthful Thunder line-up began to find their range, Shai Gilgeous-Alexander adding 10 points in the third quarter to help OKC build a 10-point cushion heading into the fourth quarter.

Oklahoma City’s barrage of scoring continued in the fourth with Jalen Williams adding 10 points as the Thunder outscored their visitors 28-16 to seal victory by a 22-point margin.

Gilgeous-Alexander led the OKC scoring, finishing with 29 points, nine rebounds and nine assists while Chet Holmgren added 19 points and Williams 18.

Kyrie Irving led Dallas with 20 points while Luka Doncic, struggling with a sore knee, finished with 19 after shooting six-of-19 from the field.

Oklahoma City, who have an average age of just over 23, are the youngest team to win a second round playoff game and were the youngest team to win a postseason series after sweeping the New Orleans Pelicans in the first round.

“We don’t worry about all the statistics and the stats, and how young we are,” Gilgeous-Alexander said after the win. “We just want to win basketball games at a high level and that’s what we focus on.

“We try to get that done every night and tonight we did so.”

Doncic said the Mavericks would need to improve dramatically for game two taking place in Oklahoma City on Thursday.

The Slovenian star brushed off questions about his own shooting performance.

“Who cares? We lost. We’ve just got to move onto the next one. I’ve got to be better, we’ve got to be better,” Doncic said.

“They’re a great defensive team and a great offensive team, so it’s not going to be easy at all. We’re going to have to play very good basketball, focused basketball, for 48 minutes.”